The energetic reign of King Razadarit of Hanthawaddy had (r. 1384–1421) had cemented the kingdom's existence.

Razadarit had firmly unified the three Mon-speaking regions together, and had successfully fended off the northern Burmese-speaking Ava Kingdom in the Forty Years' War (1385–1424), making the western kingdom of Rakhine a tributary from 1413 to 1421 in the process.

The war had ended in a stalemate but it was a victory for Hanthawaddy as Ava finally gave up its dream of restoring the Pagan Empire.

Pegu in the years following the war had occasionally aided Ava's southern vassal states of Prome and Taungoo in their rebellions but carefully avoided getting plunged into a full-scale war.

Hanthawaddy after the war had entered its golden age whereas its rival Ava had gradually gone into decline.

Hanthawaddy from the 1420s to the 1530s has been the most powerful and prosperous kingdom of all post-Pagan kingdoms.

Under a string of especially gifted monarchs—Binnya Ran I, Shin Sawbu, Dhammazedi and Binnya Ran II—the kingdom had enjoyed a long golden age, profiting from foreign commerce.

Its merchants trade with traders from across the Indian Ocean, filling the king's treasury with gold and silver, silk and spices, and all the other stuff of early modern trade.

The kingdom has also became a famous center of Theravada Buddhism.

It has established strong ties with Sri Lanka and had encouraged reforms that later spread throughout the country.

The powerful kingdom's end comes abruptly, subjected from 1534 onward to constant raids by the native Burmese Taungoo Dynasty from Upper Burma, previously ruled, since the waning of Mongol power, as a Chinese tributary under the hereditary kings of Burma’s Buddhist Shan people (linguistically, culturally and physically related to the neighboring Thais).

King Takayutpi is unable to marshal Hanthawaddy’s much greater resources and manpower against the much smaller Taungoo, led by King Tabinshwehti and his deputy general Bayinnaung.

Pegu becomes the capital of the united Burmese kingdom.