Siddhijaya Brahmadeva
Siddhijaya Brahmadeva is described in legend as a ruler of Nakhon Chai Si, which has been identified with the present-day Nakhon Pathom, functioning as the center of Kamalanka. According to tradition, Siddhijaya consolidated authority in the region by suppressing a group of Brahmans, potentially led by Kakabhadra, who had exercised power over local settlements before Siddhijaya's arrival.
Chronological discrepancies within the sources place Siddhijaya's reign in apparent overlap with that of another monarch of Nakhon Chai Si, Kakabhadra. Some scholars have therefore sought to equate the two figures. Nevertheless, the accounts provide grounds for distinguishing them: the legend records Siddhijaya as having come from Manohana and founded Nakhon Chai Si in 590 CE, whereas the describes Kakabhadra as ruling Takkasila for 72 years before he died in 641; thus his reign was 569 to 641, and his grandsons are said to have been descendants of King Tona Brahmin. This suggests a period of political overlap between the two monarchs within the same polity.
During the Sui period, the Tongdian records the existence of the Tou-he Kingdom, identified with Dvaravati, which was centered at Nakhon Pathom and ruled by a monarch referred to as Pu-xie-qi-yao of the Tou-he-luo dynasty. The relationship between this figure and the contemporaneous Dvaravati monarchs, including Siddhijaya and Kakabhadra, remains unestablished. It was during this period, approximately between 605 and 616, that Dvaravati is first recorded as having sent tribute to the Chinese court.
Founding of Nakhon Chai Si
Prior to the arrival of Siddhijaya Brahmadeva, the area corresponding to present-day Nakhon Pathom was under the authority of a group of Brahmanical leaders who established a settlement known as Tonabrahma. Within this community, a golden vessel known as the Tanan or Manohana near Yassodhon, established his seat at Tonabrahma and renamed it Nakhon Chai Si. Although legend and chronicles place the establishment of Nakhon Chai Si in 590 CE, archaeological evidence suggests that the region had already functioned as a major settlement since the 550s.The narrative also recounts that news of the Tanan reached the king of Lanka, who dispatched a monk named Kalayadishthira to obtain the vessel in exchange for relics of the Buddha. Siddhijaya Brahmadeva requested the Tanan from the Brahmanical leaders, but his petition was refused. This refusal led to conflict between Siddhijaya and the Brahmanical community, compelling him to relocate to a nearby site where he established a new city, referred to in the sources as Pawan or Panan. There he constructed a large stupa—speculated by later tradition to be Phra Pathommachedi—to enshrine the relics received from the Lankan king. Eventually, Siddhijaya seized the Tanan by force and presented it to Kalayadishthira, the emissary from Lanka.
During this period, it is recorded that Kalavarnadisharaja, the elder son of Kakabhadra, commissioned a group of Brahmans under his authority to construct the city of Lavapura in 629. The project was completed in 648. Having succeeded his father in 641, Kalavarnadisharaja subsequently relocated his seat to this newly established center and designated the polity as the Lavo Kingdom.