Narapati has remained a nominal vassal to Confederation-controlled Ava.

Although his authority does not extend beyond the immediate region around Prome, he has become ensnarled in the Toungoo–Hanthawaddy War.

An ally of King Takayutpi of Hanthawaddy, Narapati is married to Takayutpi's sister, and provides shelter to the fleeing Hanthawaddy troops in 1539.

When Toungoo troops attack the heavily fortified Prome, Narapati asks for help from the Confederation in Ava, which has neglected to intervene in the first four years of Toungoo–Hanthawaddy Wa in Lower Burma.

Now finally appreciating the gravity of the situation, the saophas finally band together and send in a force to relieve Prome.

The Confederation troops break the siege, then refuse to follow up on the retreating Toungoo armies.

Narapati forms an alliance with the Mrauk U Kingdom of Arakan by sending his sister and his queen (Takayutpi's sister) to King Min Bin of Mrauk U.

(Takayutpi had died soon after the battle.)

Narapati too dies soon after and is succeeded by Minkhaung.

Min Bin has turned Mrauk-U into a serious regional power by the late 1530s.

Not only does he control the entire Arakan littoral to Chittagong but he also has built up a powerful navy and an army that includes many Portuguese mercenaries.

He closely monitors the developments in mainland Burma with great concern, however,especially after Toungoo's unlikely victory over Hanthawaddy that gives upstart the upstart Burmese principality control of Lower Burma.

He does not want to see a strong, united Irrawaddy valley, which in the past had interfered with the coastal kingdom.

When King Minkhaung of Prome, the only holdout in Lower Burma and a vassal of the Confederation of Shan States, asks for an alliance by presenting his sister, the former queen of Hanthawaddy, Min Bin readily agrees.

Pegu becomes the capital of Tabinshwehti’s united Burmese kingdom in 1539.