He controlled only around the capital region, and unsuccessfully tried to stop the Mong Mao (Maw) Shan raids of Central Myanmar (Burma) that began in 1359.
Narathu was the third child of Princess Nan Lon Me of Pagan and Viceroy Kyawswa of Pinle.
[2] When his second elder brother Kyawswa II succeeded the throne in 1350, Narathu became the heir-presumptive.
In the north, the powerful Shan state of Mong Mao (Maw in Burmese), which had successfully thrown off the Mongol authority in 1355,[4] had been raiding the northern Sagaing Kingdom's territory at least since 1357, and just broken through into Pinya's territory (present-day Central Myanmar) in early 1359.
[2] Likewise, in the south, Pinya's erstwhile nominal vassal Toungoo (Taungoo) had not only revolted in 1358 but also raided the Kyaukse capital region.
[6] It was a complete reversal of his brother's policy but Narathu had determined that Pinya was not strong enough to control its vassals, let alone assist Sagaing in the fight against Mong Mao.
[2] In desperation, Narathu sought an alliance with Mong Mao's ruler Tho Chi Bwa (Si Kefa).
Many able men had been fleeing Central Burma since the Shan raids began,[9] and he could not mobilize a large enough army.
[10] At Sagaing, Tho Kho Bwa was deeply unsatisfied with what he considered poor performance by Pinya.