Rise of Toungoo Dynasty in
Pegu (modern day Bago, Myanmar), the city became Tabinshwehti's new capital. Burma in the 15th century was divided into four principal power centers: the
Ava Kingdom in present-day central Burma, the
Mon-speaking
Hanthawaddy kingdom on the southern coast, the
Mrauk-U Kingdom (
Arakan) in the west, and various
Shan States in the east and the north. Beginning in the 1480s, Ava began to disintegrate into even smaller kingdoms. By the early 15th century, Ava's former vassals—
Mohnyin (and its allies
Confederation of Shan States) in the north and the
Prome Kingdom (
Pyay) in the south—were regularly raiding their former overlord's territory with increasing frequency and intensity. During this period of tumult,
Mingyi Nyo, then governor of
Toungoo (Taungoo), a small region located at the southeastern corner of Ava Kingdom also declared independence in 1510, and largely stayed out of the internecine fighting in the following years. When Ava fell to the combined forces of the Confederation and Prome in 1527, many people fled to Toungoo, the only region in Upper Burma at peace. In 1530, Mingyi Nyo's son 14-year-old
Tabinshwehti succeeded him as king. Toungoo's stability continued to attract manpower from the surrounding regions, especially after 1533 when the Confederation sacked its erstwhile ally Prome. The tiny Toungoo was now the only ethnic
Burman-led kingdom, and one surrounded by much larger kingdoms. Fortunately for Toungoo, the Confederation was distracted by internal leadership disputes, and Hanthawaddy, then the most powerful kingdom of all post-
Pagan kingdoms, was weakly led. Tabinshwehti decided not to wait until the larger kingdoms' attention turned to him. In 1534, Tabinshwehti and his deputy
Bayinnaung, then a couple of 18-year-olds, launched their first
military campaign against Hanthawaddy. It was the first of a series of wars by Toungoo that would engulf western and central mainland Southeast Asia for the next 80 years. In 1538–1539, the upstart kingdom captured Hanthawaddy's capital
Pegu (Bago), and in May 1541,
Martaban (
Mottama) and
Moulmein (Mawlamyaing). Significantly, for the first time, the Burmese and the Siamese shared a common border in the upper-
Tenasserim coast. For the next six years, Toungoo was busy fighting against Hanthawaddy's allies: Prome (1542), the Confederation (1542–1544), and Prome's ally Mrauk-U (1546–1547). On the eve of the Siamese war, in 1547, Toungoo controlled a Lower Burma region from
Pagan (Bagan) in the north to Moulmein in the south. The boy's father was King
Borommarachathirat IV, Chairacha's half-brother. The child-king was subsequently executed by his uncle. King Chairacha died in 1546 after reigning for thirteen years, leaving the throne to his eleven-year-old son,
Prince Kaeofa, who was crowned King
Yot Fa. As the new king had not come of age, the role of
regent was assumed by his mother, Chairacha's
chief consort Si Sudachan (, also spelled Sri Sudachan), who was a descendant of the Uthong royal house. Chairacha's half-brother and
Uparaja, Prince
Thianracha, was another contender for the regency. To avoid court intrigues and conflict with Si Sudachan, Prince Thianracha
retreated to a
monastery as a
monk. It was also recorded that she was heavily pregnant and soon gave birth to a daughter; unable to conceal this secret, she mounted a coup, removed her son and put her paramour on the throne. He was crowned as King (or Khun)
Worawongsathirat. Worawongsathirat's reign was short. Within 42 days several nobles and government officials of Ayutthaya plotted to remove him from the throne. The conspirators were led by Khun Phiren Thorathep, a descendant on his father's side to the
kings of Sukhothai and a relation on his mother's side to King Chairacha. Thianracha was immediately invited to leave the
Sangha and assume the throne as King
Maha Chakkraphat. One of his first acts was to appoint Khun Phiren Thorathep as King of
Sukhothai (but as a
vassal to himself) with a capital at the great fortified town of
Phitsanulok. The king then bestowed upon him the title
Maha Thammaracha (a title used by the last four kings of Sukhothai), along with the hand of his daughter
Princess Sawatdirat in marriage. ==Tenasserim (1547–1548)==