The history of the Irrawaddy basin is that of several peoples, the ethnic Burmans being only one of them. On their southward move from eastern Tibet they had been preceded by the Pyu, who had established a kingdom there as early as the 3rd century. The original historical inhabitants of Lower Burma were the staunchly Theravada Buddhist Mon, with their centres at Thaton, at the mouth of the Sittang (often identified with Survarnab-humi), and at Pegu, former HamsavatI. It was only in the 11th century that the Burman kingdom of Pagan established Burman suzerainty over the Mon south, absorbing in the process many Mon cultural elements which now form the basis of the Burmese civilization. The Pyus, whose kingdom of SrIkshetra (Prome) was thus sandwiched between the Mons and the Burmans, were eventually assimilated by the latter. But the kingdom of Pagan was to last only to the end of the 13th century when it was conquered by the Mongols, in the wake of whom the Shan (i.e. Thais) rules over the area for such a long time that it could have become another ‘Thailand’ had not the Burmans once again taken the political lead in the 16th century.