Indapraṣṭhanagara อินทปรัษฐ์นคร
Ancient settlement
Country	Thailand
Province	Chai Nat province (proposed)
Traditional date of re-founding	757 CE
Identification	Disputed; variously located at Angkor or in the Phraek Si Racha region

Indapraṣṭhanagara (Thai: อินทปรัษฐ์นคร; also rendered Indaprasthanagara) is an ancient toponym attested across the chronicle and legendary traditions of several Tai-speaking societies of mainland Southeast Asia. The name appears in Central Thai, Lan Na, Lao, Isan and Khmer texts, in which the city figures variously as a royal capital, a tributary overlord, a place of dynastic refuge and a setting for Buddhist foundation narratives.

Taken together, these traditions situate the city's historical memory between roughly the late 4th^[a] and the early 14th century CE,^[b] after which the name disappears from the record with the rise of the Sukhothai and Ayutthaya kingdoms. No archaeological site has been securely identified with the toponym, and its location remains disputed.

Thai and Cambodian historiography long equated Indapraṣṭhanagara with the Angkorian capital of Yaśodharapura.^{[3]: 1, 8–9 [4]} That identification was challenged by Michael Vickery in 1995 on philological grounds,^{[5]: 191–2} and has since been questioned on chronological grounds, since the traditions place Indapraṣṭhanagara several centuries before the foundation of Yaśodharapura in the late 9th century.^[c] An alternative localization, drawing chiefly on the Ayutthaya Testimonies, places the city in the Phraek Si Racha historical region east of Sankhaburi, in the central Chao Phraya basin.^[8]: 5–6 This relocation carries wider implications for the reconstruction of relations among Sukhothai, Lavo, Angkor, Ayutthaya, and Lan Xang between the 11th and 14th centuries.

The toponym is an Indic compound of Indapraṣṭha with nagara ("city"), echoing Indraprastha, the capital of the Pandavas in the Mahabharata. Such Indic royal names were adopted widely across mainland Southeast Asia and do not in themselves indicate a link to any particular polity.

The 1932 Chronicle of the Padumasūriyavaṃśa derived the name instead from the Cambodian toponym Indrapat combined with the royal title Indrāditya, and on this basis identified the city with the Khmer capital.^{[5]: 191–2} Cambodian historiography associated it further with sruk indraparāś, a place name attested in several Angkorian inscriptions (K. 235, K. 259, K. 380). Vickery objected that the term sruk denotes a village, commune or district rather than a royal capital, and that the derivation therefore cannot support the identification.^[5]: 192

The sources in which Indapraṣṭhanagara appears are chronicles, legends and testimonies compiled well after the periods they describe; the dates they assign to the city are retrospective, and several traditions preserve mutually incompatible accounts. They are grouped below by cultural tradition.

Attestations of Indapraṣṭhanagara by tradition

Source	Tradition	Period assigned	Role of the city
Legend of Singhanavati; Yonok Chronicle [th]	Lan Na	late 4th–5th c.	Refuge of forces defeated by Phrom of Yonok
Legend of Khun Borom; Lan Xang Chronicle	Lao	7th c.; 14th c.	Foundation by a son of Khun Borom; refuge of Fa Ngum
Chronicle of the Padumasūriyavaṃśa	Central Thai (1932)	8th–9th c.	Royal capital of the Padumasūriyavaṃśa line
Ayutthaya Testimonies	Central Thai	8th–13th c.	Overlord of Sukhothai; located east of Sankhaburi
Northern Chronicle; Legend of Phra Ruang	Central Thai	10th–11th c.	Tribute-receiving overlord of Lavo
Legend of Nakhon Si Thammarat [th]	Southern Thai	11th–12th c.	Seat of Sri Dharmasokaraja I before his move south
Legend of Phaya Khan Khak [th]	Isan	undated	Realm of King Ekajara; setting of a drought narrative
Legend of Preah Thong–Neang Neak	Khmer	undated	Settlement founded after the couple's marriage

The Chronicle of the Padumasūriyavaṃśa, compiled in 1932, dates the establishment of Indapraṣṭhanagara to the early 8th century.^[d] According to the text, the infant prince Ketumāla and his mother were expelled by his father, Gomerāja, ruler of Pranagara Khemarājadhānī (พระนครเขมราชธานี).^[3]: 2 When the prince was three, mother and son founded a settlement on the forested frontier of that kingdom near the Dong Phaya Fai range and named it Indapraṣṭhanagara. After Ketumāla repeatedly refused to return to the capital, his father formally enthroned him there as a local ruler.^[3]: 4–5

Ketumāla is said to have adopted Padumasūriyavaṃśa, who founded a second settlement on accreted land, likewise named Indapraṣṭhanagara, and ruled from it after his adoptive father's death.^[3]: 4–5 The chronicle gives no absolute dates, but Padumasūriyavaṃśa has been identified with a figure named in 17th-century European accounts of Siam — Du Royaume de Siam and the Instructions Given to the Siamese Envoys Sent to Portugal in 1684 — which place his enthronement in 757 CE.^{[10]: 38 [12]: 127 [11]}

The concluding portion of the chronicle, which equates Indapraṣṭhanagara with Angkor, recounts that a cattle trader named Phrom was raised to the throne, founded a new city east of the river, made it his principal seat, and reigned twenty years before being succeeded by an unnamed son.^{[13]: ๓๕–๖} This episode has been cited against the Angkorian identification, since Angkorian epigraphy records succession within established royal lineages and does not attest the accession of a commoner of mercantile background.

The Ayutthaya Testimonies give the most geographically specific reference, placing Indapraṣṭhanagara east of Sankhaburi in the Phraek Si Racha historical region,^[8]: 4–5 an area corresponding broadly to the central Menam basin and the Si Thep zone. The text also states that the city already existed before the reign of Padumasūriyavaṃśa,^[8]: 6 conventionally dated from 757 CE.^[d]

Two passages indicate that Indapraṣṭhanagara was distinct from neighbouring polities sometimes conflated with it. The Ratanabimbavaṃsa records that Adītaraj of Ayojjhapura, often identified with Si Thep,^[14] campaigned against Indapraṣṭhanagara while the latter was suffering a severe flood following the death of its great king,^{[15]: 94 [14][16]: 51} while the Chronicle of the Padumasūriyavaṃśa lists Lavo, also east of Phraek Si Racha, as a tributary of Indapraṣṭhanagara.^[3]: 8 On this reading the three were separate polities.^[14]

A version of the Legend of Phra Ruang preserved in the Northern Chronicle concerns Sricandradhipati, also known as Phra Ruang II of Sukhothai (r. 959 – early 11th century). In this account he was a commoner of Lavo charged with collecting tribute for delivery to Indapraṣṭhanagara; after the king of Indapraṣṭhanagara ordered his arrest he fled to Sukhothai, where he later rose to kingship.^{[17]: 27–9}

The same chronicle names the ruler of Indapraṣṭhanagara as Phraya Kreak (พญาแกรก), also called Sindhob Amarin.^[17]: 68 In the passage on Sai Nam Peung in the Ayutthaya Testimonies, Phraya Kreak appears instead as ruler of Phraek Si Racha, there called Phra Nakhon Sawan Buri (พระนครสวรรค์บุรี),^[8]: 35 who took the regnal title Sindhob Amarin after conquering Mueang Wat Derm (เมืองวัดเดิม, later Ayodhya).^{[17]: 30–3}

The Northern Chronicle also relates that Anuruddha, king of Arimadhanapuri, identified by scholars with ancient Nakhon Pathom in the lower Chao Phraya basin,^{[18]: 4 [1]: 6} travelled to Sri Lanka and returned with a Buddha image and copies of the Tipitaka. The vessel carrying them lost its course and arrived instead at Indapraṣṭhanagara; Anuruddha demanded their return, but only the scriptures were surrendered, the image being retained^{[17]: 93–7} and later associated with a major flood at the city.^{[17]: 99–101}

The Legend of Nakhon Si Thammarat [th] records that Sri Dharmasokaraja I, king of Indapraṣṭhanagara, fled southward in 1117 with his brother Candrabhānu I (Sri Dharmasokaraja II)^[e] and his son Vaṃśasurā I (Sri Dharmasokaraja III) in the face of severe epidemic disease and demographic collapse in the royal city.^[19]: 37 He is said to have re-founded Nakhon Si Thammarat as his new seat.^{[19]: 37 [21]: 28}

An alternative version presents Sri Dharmasokaraja I as a foreign ruler whose origins lay in Hanthawaddy,^[21]: 28 then under Pagan suzerainty,^[22]: 33 who established a royal centre at Indapraṣṭhanagara, governed the surrounding Menam basin, and transferred his power base to Nakhon Si Thammarat, which he had re-founded in 1077, after the epidemic of 1117.^{[19]: 37–40 [21]: 28}

The Yonok Chronicle [th] and the Legend of Singhanavati, in their accounts of the legendary Yonok monarch Phrom (r. 379–444), place Indapraṣṭhanagara within the Chao Phraya basin with direct access to the sea, and describe it as the region into which the Khom retreated after their defeat by Phrom.^{[1]: 82 [15]: 166} This is the earliest of the attestations in narrative time.^[a]

The Lao Legend of Khun Borom attributes the founding of Indapraṣṭhanagara to Khoun Kôm (ขุนกม or ลกกม), a son of Khun Borom,^[2]: 5 whose floruit David K. Wyatt tentatively placed in the 7th century.^[23]

The Lan Xang Chronicle records a later episode in the early 14th century, when Khun Yak Fah (ขุนยักษ์ฟ้า), also called Khun Phi Fa (ขุนผีฝ้า), father of Fa Ngum, was expelled from Muang Sua.^[2]: 8 Fa Ngum accompanied him into exile at Indapraṣṭhanagara, where he was adopted by its ruler Siri Juntarat (ศิริจุนทราช) and married the ruler's daughter Nang Yad Kham (นางหยาดคำ). The military support he received through this patronage enabled the campaigns that culminated in the foundation of Lan Xang in the mid-14th century.^[2]: 9

The Roi Et–Yasothon and Sisaket recensions of the Legend of Phaya Khan Khak [th] name the ruler of Indapraṣṭhanagara as King Ekajara (เอกราช),^[24] who appears in the Ayutthaya Testimonies as ruler of Muang Sing and of the same lineage as Phra Phanom Thale Seri of the Padumasūriyavaṃśa dynasty.^{[8]: 45–6} Ekajara's son was born with rough, pitted skin resembling a toad's, whence his epithet Phaya Khan Khak (lit. 'the Toad King'); through adherence to the Dharma and observance of the dasavidha-rājadhamma his appearance was restored on his accession. He then led an expedition against King Taen (พญาแถน) of the Mekong basin, who was able to withhold rain from the Mun–Chi basins and from Indapraṣṭhanagara for several years.^[24]

The description parallels that of the King of Bāla (พาละ) in the Chronicle of the Padumasūriyavaṃśa, who succeeded his father Padumasūriyavaṃśa at Indapraṣṭhanagara in 800 CE. The accounts differ in that the King of Bāla was born with normal skin that later became pitted through illness before being cured by a r̥ṣi; the chronicle also credits him with victories over a Nāga king who was his maternal grandfather.^{[3]: 10–3}

This section needs expansion. You can help by adding missing information. (August 2026)

The Khmer Legend of Preah Thong–Neang Neak relates that Preah Thong married Neang Neak and that the couple founded a new settlement;^[25]: 59 in certain recensions — some of which parallel the Chronicle of the Padumasūriyavaṃśa — that settlement is identified as Indapraṣṭhanagara.

Later Cambodian scholarship dated the narrative to the Funan period by equating Preah Thong with Kaundinya I, the Brahmin prince of Chinese sources, and Neang Neak with Soma, the nāga princess of the Funanese foundation myth.^[26]: 101 Michael Vickery instead read the legend as a later adaptation of Ayutthayan foundation traditions, particularly the Uthong legend, subsequently absorbed into Cambodian mythology, noting that thong (ทอง, "gold" in Thai) is unattested in Old Khmer before the 14th century.^[26]: 101

No inscription names Indapraṣṭhanagara directly. Four bodies of epigraphic material have nonetheless been brought to bear on its identification.

• Dong Mae Nang Mueang inscription (K. 766). Found north of the Phraek Si Racha region in present-day Nakhon Sawan province and dated to 1167 CE, it records Sri Dharmasokaraja I as deceased and attests the succession of Sri Dharmasokaraja II.^{[19]: 38 [20]} Read together with the Legend of Nakhon Si Thammarat, it has been taken to suggest that Sri Dharmasokaraja II sought to recover his father's former northern territories in the Phraek Si Racha and Lavo regions,^[19]: 40 and thus to support a location in the lower Menam valley.
• Angkorian inscriptions K. 235, K. 259 and K. 380, which attest the toponym sruk indraparāś; Vickery held that sruk designates a subordinate rural unit and cannot denote a capital.^[5]: 192
• Wat Kok Svay Chek inscription (K. 754), the earliest Pali inscription from Angkor securely associated with Theravāda, dating to the reign of Srindravarman (r. 1295–1308).
• Sukhothai inscriptions. The Sukhothai Inscription No. 1 of Ramkhamhaeng (r. 1279–1298) records dynastic ties extending to Vientiane and Luang Prabang and places Phraek Si Racha (เมืองแพรก) within the Sukhothai sphere. The Khao Sumanakut Inscription (จารึกเขาสุมนกูฏ; Inscription No. 8), of the reign of Maha Thammaracha I (r. 1347–1368), sets Sukhothai's eastern limit at the territory of "Phraya Thao Fa Ngom", identified with Fa Ngum.

The equation of Indapraṣṭhanagara with Yaśodharapura was first articulated in the Chronicle of the Padumasūriyavaṃśa, composed in 1932,^[3] on the etymological grounds set out above. It was reinforced by later Thai and foreign scholarship, including the 1957 Thai recension of the Lan Xang Chronicle,^[2]: 8–9 and by Cambodian historiography through the sruk indraparāś inscriptions.^[5]: 192 It remains the mainstream position in Thai scholarship despite Vickery's critique of 1995.^{[5]: 191–2}

It has been observed that the apparent convergence of Thai and Cambodian traditions on this point does not constitute independent corroboration, since the Cambodian reception of the equation postdates a period of substantial Siamese cultural influence at the Cambodian court.

The inferred accession of Padumasūriyavaṃśa in 757 CE^[d] precedes the accepted foundation of Yaśodharapura in the late 9th century by nearly two centuries.^[c] Indapraṣṭhanagara is moreover named in connection with the reign of Phrom of Yonok, conventionally placed in the 3rd–4th centuries^[1]: 85 of the Shaka era^[27] (4th–5th centuries CE), some four to five centuries earlier still.

The political geography of the period presents a further difficulty. Vickery characterized the Tonlé Sap basin of the 8th century as politically fragmented,^[28]: 6 whereas the Thai traditions depict the reign of Padumasūriyavaṃśa as one of territorial consolidation encompassing Lavo, Sukhothai and Talung (เมืองตลุง).^[3]: 8

The Chronicle of the Padumasūriyavaṃśa and the Phra That Phanom Chronicle portray the rulers of Indapraṣṭhanagara as patrons of the Buddhist saṅgha whose merit drew neighbouring polities into tributary relations founded on devotional allegiance rather than conquest. Such a portrayal presupposes a region in which Theravāda already supplied the principal source of royal legitimacy.

The religious landscape of the Tonlé Sap basin in the same period is not consistent with that premise. Contemporary inscriptions attest a predominantly Śaiva and Vaiṣṇava court religion under the Chenla rulers, and such Buddhist practice as is attested — for instance the Avalokiteśvara dedications recorded near Siem Reap in 791 CE — belongs to the Mahāyāna tradition. The earliest securely Theravāda Pali inscription from Angkor, K. 754, dates only to the reign of Srindravarman (r. 1295–1308).

The Northern Chronicle account of Anuruddha of Arimadhanapuri has been read as incompatible with an Angkorian location. Under that identification, a vessel returning from Lanka to Nakhon Pathom would have entered the Gulf of Thailand and then drifted to Angkor, and Anuruddha's subsequent demands would have required sustained communication between Nakhon Pathom and Angkor across separate river systems. If Indapraṣṭhanagara lay in the Phraek Si Racha region, both the navigational error and the diplomatic exchange become straightforward, since Nakhon Pathom and Phraek Si Racha share an interconnected waterway network reached from the Gulf by way of the Chao Phraya.

A related difficulty arises from the identification of Anuruddha of Arimadhanapuri with Anawrahta of Pagan (r. 1044–1077), proposed on phonetic grounds.^[17]: 93 The Jinakalamali associates Anuruddha directly with Camadevi of Haripuñjaya,^[29]: 128 conventionally dated to the mid-7th century, roughly four centuries before Anawrahta. If Arimadhanapuri is taken as Pagan rather than Nakhon Pathom, the geography becomes less plausible still: a vessel returning from Sri Lanka to Pagan would sail north through the Bay of Bengal and up the Irrawaddy River, whereas Angkor lies to the south-east in a separate drainage reached by the Mekong or Tonlé Sap.

The Legend of Singhanavati adds a further inconsistency, situating Indapraṣṭhanagara in the Chao Phraya basin and associating it with the southward retreat of forces defeated by Phrom of Yonok toward present-day Kamphaeng Phet.^[1]: 82

An alternative localization places Indapraṣṭhanagara in the Phraek Si Racha region east of Sankhaburi, on the basis of the geographical indications in the Ayutthaya Testimonies^[8]: 5–6 together with the narrative traditions concerning Sri Dharmasokaraja I and II^[19]: 37 and the evidence of K. 766.^[20]

Under the Phraek Si Racha localization, the Ayutthaya Testimonies record Sukhothai as a long-standing tributary of Indapraṣṭhanagara, with obligations maintained since the reign of Padumasūriyavaṃśa.^[3]: 8 The lapse of these payments during the reign of Candraraja (r. 1184–1214) broke the established order and precipitated the confrontation that led to Sukhothai's de facto independence in about 1208.^{[8]: 15–6}

In this period Phraek Si Racha has been identified with the polity known in Chinese sources as Chen Li Fu,^{[30]: 9, 15 [31]: 20–3} which existed from roughly 1180 to the early 13th century.^{[32]: 1–6} The conflict with Sukhothai coincides with the reign of Se-li-Mo-hsi-t'o-pa-lo-hung or Mahīdhāravarman of Chen Li Fu, which began in 1204/05.^[32]: 7

Both Indapraṣṭhanagara and Chen Li Fu disappear from the record in these years, coinciding with Uthong II's consolidation of authority over Ayutthaya and the southward relocation of the royal seat in 1205. A connection has been suggested between Uthong II's father Phanom Thale Sri, said to have married a mixed Cham-Chinese princess, and the earlier Chen Li Fu ruler recorded as Fang-hui-chih, who sent an embassy to the Chinese court at a time when tributary missions from Southeast Asia were otherwise not being received.

The Ayutthaya Testimonies describe the royal houses of Indapraṣṭhanagara and Sukhothai as belonging to a single lineage,^{[8]: 16–7} and present the earlier rulers of the Menam valley — the Phraek Si Racha line — as progenitors of both the Sukhothai and Ayutthaya dynasties.^[f] Walailak Songsiri has further associated the rulers of Chen Li Fu with Phimai and the Angkorian Mahidharapura lineage.^[30]: 6 On this reading, Sukhothai, Ayutthaya, Angkor and Indapraṣṭhanagara appear as interconnected polities linked by dynastic alliance rather than as isolated or uniformly antagonistic states.

The same framework bears on accounts of the defeats inflicted on Phraek Si Racha rulers by Sri Dharmasokaraja II in the Lavo region in 1157 and in Phraek Si Racha in 1167, after which two princes are recorded as withdrawing northward into the upper Menam basin: Suryaraja, grandfather of Si Inthrathit, to the area of modern Kamphaeng Phet,^[8]: 11 and Pra Poa Noome Thele Seri to the Sukhothai–Nakhon Thai region.^{[11][12]: 127} These movements form part of the longue durée processes behind the emergence of the Sukhothai Kingdom in the 13th century.

Following the decline of the Phraek Si Racha dynasty, Angkor under Jayavarman VII intervened militarily and took Lavo in 1180.^[19]: 39 In the same year a former Siamese ruling house under Fang-hui-chih, identified with Pra Poa Noome Thele Seri and probably allied with the Mahidharapura dynasty,^[30]: 6 seized Phraek Si Racha from Sri Dharmasokaraja II and re-established the polity as Chen Li Fu.^[32]: 18 The Legend of Nakhon Si Thammarat further records an attempt by the same ruler to invade Tambralinga, by then the only remaining dominion of Sri Dharmasokaraja II after his defeat in the Menam basin.^[19]: 41

Evidence adduced for such alliances includes the marriage of Pha Mueang of Sukhothai to Princess Sukhara Mahādevī, a relative of Jayavarman VII;^[34] depictions of Xiān (Siamese) mercenaries in the Angkor Wat reliefs;^[35]: 70 the large Siamese population recorded at Yasodharapura in the 13th century by Zhou Daguan;^[36][37] and the Buddha images dispatched by Jayavarman VII to polities of the Menam basin, as attested in the Preah Khan inscription (K. 908).^[38]: 58 Also cited are a week-long religious observance undertaken after 1188 by Pra Poa Noome Thele Seri at Lavapura,^[8]: 47 then under Angkorian control,^[19]: 39 and the accession of his descendant Uthong II at Ayodhya in 1205^[39] — territory previously held by Chen Li Fu^[g] — without recorded conflict.

Within this framework, figures such as Khom Sabat Khlon Lamphong, traditionally cast as Angkorian officials who usurped Sri Naw Nam Thum of Sukhothai, may instead represent rivals aligned with a competing domestic faction. This reading accords with scholarship treating early Sukhothai and Angkor as linked by dynastic alliance rather than defined by rivalry.^{[40]: 58 [41]}

The version of the Legend of Nakhon Si Thammarat presenting Sri Dharmasokaraja I as a ruler of Hanthawaddy origin^[21]: 28 corresponds closely to the Northern Chronicle account of late Dvaravati events: the extension of Pagan influence into the Menam basin between the 1050s and 1080s, the establishment of the Pagan noble Kar Tayy (r. c. 1081–1121) at Suphannaphum,^[17]: 60 the invasion of Ayodhya in 1087 and the death of King Narai I,^{[17]: 40–2 [39]} and a two-year interregnum before the accession of Phra Chao Luang, a ruler of uncertain origin.^{[17]: 41–2} The recorded northward removal of the Siamese ruler Surindraraja (r. 1062–1100) from Phraek Si Racha to Chai Nat in the same period^[8]: 41 has been read as part of the same upheaval.

These local records of Pagan penetration between the 11th and late 12th centuries are consistent with the early 13th-century Chinese Zhu Fan Zhi, which places Pagan on Chenla's western border,^[42]: 99 and with Burmese traditions recording repeated conflict between Pagan and Angkor under Anawrahta (r. 1044–1077), including claims of a temporary seizure of Angkor itself.^[22]: 34 They accord further with the interpretation that Tambralinga under Sri Dharmasokaraja I and his successors lay under Pagan suzerainty from the mid-11th to the early 13th century.^{[43]: 89–90 [44]: 61}

The Lan Xang Chronicle account of Fa Ngum's adoption by Siri Juntarat of Indapraṣṭhanagara^[2]: 8–9 has conventionally been read alongside the Angkorian identification, implying that the forces behind the foundation of Lan Xang came from Angkor.

Several difficulties have been raised against that reading. The mid-14th century was a period of marked contraction at Angkor: the last Sanskrit inscription dates to the reign of Indrajayavarman (r. 1308–1327), a dynastic change in 1336 severed continuity with the preceding lineage, and Zhou Daguan had already recorded severe damage from Siamese campaigns at the time of his visit in 1296–1297. The foundation of Lan Xang in 1353 moreover falls within a period of direct Ayutthayan occupation of Angkor: after campaigns in 1350 and 1351 during the reign of Lampong Reachea [fr] (r. 1347–1352/53), Ayutthaya installed a succession of Siamese governors — Ba Sat [th] (1352/53–1356), Ba Aat [th] (1356–1357) and Kadum Bongphisi [th] (1357).

The proposal that Fa Ngum's patron was instead Jayavarman IX (r. 1327–1336) raises its own problems, since Jayavarman IX was deposed by Trasak Paem in 1336, seventeen years before the foundation of Lan Xang; the successor dynasty would then have had to tolerate the ward of the ruler it had overthrown and to commit forces to his campaigns in the 1350s.

The direction of Lan Xang's early expansion has also been cited. Effective settlement and administrative control were concentrated in the upper Mekong basin and its western approaches, with garrison communities at Mueang Sai Khao (Ban Sai Khao, บ้านทรายขาว, Wang Saphung district) and Mueang Nong Bua facing the Ayutthayan frontier rather than Angkor.^[45] Southern Laos remained loosely integrated: Photisarath (r. 1520–1548) undertook a pilgrimage to That Sikhottabong and improvements at That Phanom in 1539 to strengthen Lan Xang's southern presence, and Setthathirath (r. 1548–1571) disappeared on an expedition thought to have reached near Attapeu.

Sukhothai epigraphy, by contrast, places the Siamese sphere of the period as extending north into the upper Mekong basin, with Inscription No. 1 recording ties as far as Vientiane and Luang Prabang and naming Phraek Si Racha within the Sukhothai sphere, and Inscription No. 8 setting Sukhothai's eastern limit at Fa Ngum's territory. Under the Phraek Si Racha localization, Siri Juntarat would accordingly be a governor within the Sukhothai network rather than an Angkorian ruler, and the military support behind Fa Ngum's campaigns would derive from the Sukhothai-Siamese sphere.

Subsequent diplomacy has been read in the same sense. After the foundation of Lan Xang, Fa Ngum's forces advanced against Ayutthayan territory, and Ayutthaya responded by invoking shared dynastic kinship, sending a princess in marriage and concluding a boundary agreement, rather than treating Lan Xang as an extension of an Angkorian adversary; nor did Fa Ngum act to relieve Angkor from Ayutthayan occupation, despite the obligations that adoption, marriage and military patronage would have created.

• Dvaravati
• Chen Li Fu
• Phraek Si Racha
• Lavo Kingdom