Sivasagar district (Pron: ˈsɪvəˌsʌgər or ˈʃɪvəˌsʌgər), formerly known as Sibsagar, is one of the 34 districts of Assam state in Northeast India. Sivasagar city is the administrative headquarters of this district. This historic place is also known for its rich biodiversity. The districts covers an area of 2668 square kilometers (of the total area of 78438 square kilometers of Assam). The district comprises two sub-divisions – Sivasagar and Nazira. The district of Sivasagar lies between 26.45°N and 27.15°N latitudes and 94.25°E and 95.25°E longitudes. The district is bounded by the Brahmaputra River to the north, Nagaland to the south, the Charaideo district to the east and the Jhanji River to the west. The Sivasagar district has acquired its distinct identity due to the co-existence of different races, tribes, languages and cultures. The Sivasagar was established by Ahoms. Before the arrival of Ahoms, the area under the district was inhabited by the indigenous Tibeto-Burman tribes like Borahis and Morans. Before the British period, the center of administration of Assam was around Sivasagar were the famous Ahoms ruled for nearly six hundred years. The Ahom kings took keen interest in building different temples, dedicated to various deities and which were usually flanked by large tanks which until today stand out as memorials to their glory in the district. Sivasagar, or Rangpur as it was known then, was the capital of the Ahom Kingdom from 1699 to 1788. The famous Joysagar Tank was excavated within 45 days by Rudra Singha (1696-1714) in memory of his mother Joymoti Konwari. The Joy Dol is situated on the bank of the Joysagar Tank. Pramatta Singha (1744-1751) built the Ranghar with bricks in 1745. Gaurisagar Tank is situated at a distance of about eight miles from Sivasagar town. The Sivasagar Tank was excavated by queen Ambika Devi in 1733. The Siva Dol, Vishnu Dol and Devi Dol are situated on the bank of the Sivasagar Tank. Rajeshwar Singha (1751-1769) built the Kareng Ghar in Gargaon.