Sivasagar, formerly known as Rangpur, was the capital of the Ahom Kingdom from 1699 to 1788. The Ahoms ruled Assam for six centuries, until their kingdom fell to the Burmese in 1819 and their ruling class was all but wiped out. The province was liberated by the British in 1825 but, owing to the state of anarchy which prevailed, it was completely annexed in 1826. For administrative purposes it was divided into three sub-divisions. It is said that the original name of Sivasagar was - 'Kalansupar' after the name of 'Kalansu Gohain' who resided in a village originally existed in the place where currently the Sivasagar tank is located. 

Earlier the Sivasagar town was bounded by Cherekapar on the east, Kathpar on the west, Joyrapar in the north and Dhuliapar on the south. Till the fag end of the Ahom rule the name Shivpur persisted. Only after the treaty of Yandaboo in 1826 A.D. when the East India Company and for that matter, the British government came to hold power, Shivpur along with Rangpur came to be known as Sibsagar. During the British rule, the Sibsagar district comprised three sub-divisions: Sibsagar, Jorhat and Golaghat. In 1912 A.D. the district headquarter was again shifted to Jorhat leaving Sibsagar only as a sub-divisional headquarter. It remained so till 1983 when on 1 July that year the Sibsagar and Golaghat sub-division of undivided Sibsagar district were declared as new districts by the Government of Assam.