Pyu city-states
Beikthano ( ) situated in the irrigated Minbu region (near present-day Taungdwingyi) with direct land access to the well-watered Kyaukse plains to its northeast, is the oldest urban site so far discovered and scientifically excavated site. Its remains—the structures, pottery, artefacts, and human skeletons—date from 200 BCE to 100 CE. Named after the Hindu god Vishnu, the city may be the first capital of a culturally and perhaps even politically uniform state in the history of Burma. It was a large fortified settlement, measuring approximately 300 hectares inside the rectangular (3 km by 1 km) walls. The walls and fortifications along it measured six meters thick, and are radiocarbon dated to a period between 180 BCE and 610 CE. Like most subsequent cities, the main entrance of the walls led to the palace, which faced east. Stupas and monastic buildings have also been excavated within the city walls.
Prehistory of Myanmar
The Burmans who had come down with the early 9th Nanzhao raids of the Pyu states remained in Upper Burma. (Trickles of Burman migrations may have begun as early as the 7th century.) Like that of the Pyu, the original home of Burmans prior to Yunnan is believed to be present-day Qinghai and Gansu provinces. After the Nanzhao attacks had greatly weakened the Pyu city-states, large numbers of Burman warriors and their families entered the Pyu realm in the 830s and 840s and settled at the confluence of the Irrawaddy and Chindwin rivers, perhaps to help Nanzhao pacify the surrounding countryside. Over the next two hundred years, the small principality gradually grew to include its immediate surrounding areas— to about 200 miles north to south and 80 miles from east to west by Anawrahta's accession in 1044. Historically verifiable Burmese history begins with Anawrahta's accession.