and archaeological remains in Basistha and other archaeological locations of mythological importance. The Ambari excavations trace the time period of the city of Guwahati between the 2nd century BCE and the 1st century CE, in the Shunga-Kushana period of Indian history. Descriptions by Xuanzang (Hiuen Tsang) reveal that during the reign of the Varman king Bhaskaravarman (7th century CE), the city stretched for about 30 li (). Archaeological evidence by excavations in Ambari, and excavated brick walls and houses discovered during construction of the present Cotton College's auditorium suggest the city was of economic and strategic importance until the 9th–11th century CE. Medieval history Forces of Muhammad bin Bakhtiyar Khalji suffered a disastrous defeat in the hands of Raja Prithu in Kamrup during Tibetan expedition. The entire army of Bakhtiyar Khalji was defeated by native forces, which forced him to retreat. For short periods Guwahati was a Mughal station at the time of their occupation of Kamrup (1633-59, 1662-69, 1679- 81 A.D.). After Battle of itakhuli, Guwahati permanently came under the seat of the Borphukan, the civil-military authority of the Lower Assam region appointed by the Ahom kings. The Borphukan's residence was in the present Fancy Bazaar area, and his council-hall, called Dopdar, was about to the west of the Bharalu stream. The Majindar Baruah, the personal secretary of the Borphukan, had his residence in the present-day deputy commissioner's residence. From the time of Gadadhar Singha the ahom kings paid their attention in building several temples in various religious sites at GUwahati: Kamakhya, Aswakranta, Sukreswar, Umananda, Dirgheswari, Vasisthasram and also adorned its various entry passes with masonry gates. The Mughals invaded Assam seventeen times, but were defeated by the Ahoms in the Battle of Itakhuli and the Battle of Saraighat in outskirts of Guwahati.There was an ancient boatyard in Dighalipukhuri, probably used by the Ahoms in medieval times. Medieval constructions include temples, ramparts, and other structures in the city. Colonial history During the 17th century Guwahati was taken and retaken by Muslims and Ahoms eight times in fifty years, but in 1681 it became the residence of the Ahom governor of lower Assam, and in 1786 the capital of the Ahom raja. On the cession of Assam to the British in 1826 it was made the seat of the British administration of Assam, and so continued till 1874, when the headquarters were removed to Shillong in the Khasi hills. Modern