[2][3] Via royal intermarriage, it was also considered the sister city of Sema [fr], the capital of the neighboring state, Canasapura, located eastward on the opposite side of the Dong Phaya Yen Mountains in the Mun River basin.

[9] In the first archaeological phase (c. 4th–5th century CE), the early settlement of Si Thep occupied the inner town and there was a burial tradition with offerings related to India and communities to the central region and Moon River basin to the northeast.

As the monarchy emerged, Vaishnavism took an important role in Si Thep's society, with relationships to India, Funan, Chenla, and Dvaravati cultures.

An irrigation system was developed, and Mahayana Buddhism influenced art as relationships with India, Dvaravati and northeastern cities continued.

[10] The growth of Si Thep led to the establishment of its neighboring city, Tha Rong (Thai: ท่าโรง), located 20 kilometers northward on the bank of the Pasak River, which was later renamed Wichian Buri during the reign of King Nangklao of Rattanakosin.

[13] Via Buddhism, several historical evidences supports the connection between Si Thep and another group of Dvaravati-influenced political entities in present Northeast Thailand, Wen Dan.