King Tabinshwehti (1531-1550) was the king who unified Myanmar and reigned from 1531 until 50. He was the second monarch of the Taungoo dynasty, which his father, Minkyinyo, had founded in 1486. In 1535 Tabinshwehti began a military campaign against the kingdom of Bago in southern Myanmar, capturing the city of Pathein in the Ayeyarwaddy delta.
Four years later Bago fell, and Takayutpi, the Bago king, fled to Pyay. Employing Portuguese soldiers of fortune, Tabinshwehti captured the towns of Martaban and Mawlamyaing in 1541, and in the following year he took Pyay. With most of the southern princes his vassals, he dominated southern Myanmar as far south as Dawei on the border of Siam (Thailand).
Although Tabinshwehti's campaigns in southern Myanmar were extremely savage, he adopted many Mon customs, incorporated Mon soldiers into his army, and made the ancient city of Bago his capital in 1546. The king planned to use Myanmar as a base from which to invade Siam. His first campaign outside of Myanmar, however, was in Rakhine, the kingdom to the west of the Ayeyarwaddy delta, where he attempted to place a subservient local prince on the throne; his siege of the capital at Myohaung was suspended after the Siamese attacked Dawei, forcing him to return home. In 1548 he besieged Ayutthaya, the Siamese capital, but was forced to make an ignominious retreat to Myanmar.
Suffering defeat in two campaigns, Tabinshwehti gave himself up to drink, leaving to his brother-in-law, Bayinnaung, the task of suppressing a southern revolt. In 1550 Tabinshwehti was assassinated by a rival prince, who proclaimed himself king at Bago. Bayinnaung crushed the revolt and carried on his brother-in-law's work of unifying Myanmar.