[3] The name Bhismaknagar was first observed in the Assam District Gazetteer of the year 1928[4]—reference to a work by the 16th-century seer Sankardev that was popular in the Sadiya region (which eventually found its way into the later Chutia chronicles.

)[note 1] Historically, the region was known as Sadhayapura (the rulers being Sadhayapur-ishwar) as per copper inscriptions[7] and the fort formed part of the capital region of the Chutia king Laksminarayana,[8] also known as Che-lung in Tai Buranjis (meaning "Great City" in English).

[9] Bhismaknagar has been identified with Sadhayapuri (or Svadhayapuri), the political centre of the Chutia Kingdom.

[10] Based on an inscriptions on brick, it is assumed to have been the capital of Chutia king Lakṣmīnārāyaṇa, of the early 15th century.

[15] The Bhismaknagar central complex extended over an area of 1860 square meters and displays three halls, six ingresses and two extension rooms.