Nyaungyan spent the rest of his reign reacquiring the cis-
Salween Shan States. By his death in 1605, he had conquered all of the cis-Salween Shan states. His eldest son Anaukpetlun emerged as an able military leader, and won several key decisive victories for his father.
Mohnyin and Mogaung (1599–1600) Nyaungyan's first target was the northernmost Shan states of
Mohnyin and
Mogaung in present-day
Kachin State. On , Anaukpetlun and his 2,000-strong invasion army left Ava for the front. The
saopha (chief) of Mohnyin submitted without a fight but the
saopha of Mogaung resisted from a fortified garrison atop of a nearby hill near Mogaung. About a month later, an agreement that allowed him to keep his office as a vassal of Ava was reached. The vassalage was likely nominal. The chief would revolt again in 1604.
Nyaungshwe (1601) Nyaungyan's drive into the Shan states was briefly interrupted by the short war with Toungoo over Yamethin in October 1600. After Yamethin was retaken, Nyaungyan decided to attack
Nyaungshwe, a sizable and strategically located state next door to Yamethin. The Shan state controlled 39 vassal towns, and was located next the powerful state of
Mone in the south and Hsipaw in the north. On , Nyaungyan and his small army (seven regiments consisted of 3500 men, 400 horses, 30 elephants) invaded. The invasion is an example in which Ava's musket corps proved their worth. Nyaungshwe forces drove back three vanguard regiments trying to take an outer garrison located about 3 km from the town. The rout was such that only one third of the troops reportedly returned. Nyaungshwe forces came out of the garrison, pinning a fourth Ava regiment. But the Ava command brought out their musketeers, and counterattacked, causing heavy casualties on the enemy. Nyaungshwe forces rushed back for the safety of the walls of Nyaungshwe but were cut off by Anaukpetlun's regiment. Totally surrounded, the
saopha surrendered and submitted. But Nyaungyan reappointed him to his office. The 39 towns of Nyaungshwe now came under Ava. The extradition "shows the final abandonment of the Chinese claim to overlordship in Upper Burma". Over the next year, Nawrahta Minsaw went on to drive out
Lan Xang and its allies from eastern Lan Na. By June 1603, Lan Na was again united, albeit under Siamese suzerainty. Concerned that Mone, located immediately north of Lan Na, could be next, Nyaungyan prepared to get there first. Nyaungyan did not expect Mone, a major state with a sizable force, to be a pushover. On , after a relic chamber dedication ceremony at the Sanda Muni Pagoda in Ava, the king left for the front with a 6000-strong army. Anaukpetlun came with him. His second son Thalun stayed behind at Ava with a garrison. Afterwards, scores of Ava battalions fanned out to receive the allegiance from 37 vassals of Mone, which included Mobye (present-day northern
Kayah State) to those along the Lan Na border. The king arrived back at Ava on the New Year's Day of 966 ME, .
Instabilities and Siamese threat (1604–05) Despite the success, Nyaungyan's hold over the cis-Salween states was still extremely weak. As soon as he got back to Ava, the king was greeted with reports of unrest along the Chinese border. With a Siamese attack on Mone still highly probable, he initially decided to live with the unrest for the time being. On , he ordered a campaign to quell unrest in the northern states that would begin on . He was greatly relieved when Anaukpetlun was able to score a quick decisive victory, and captured the rebel saopha and his family.) Ava was in a bind. The court initially announced on that his majesty himself would lead the campaign to Bhamo and Hsenwi. But the campaign was indefinitely postponed due to reports of 20 Siamese army regiments led by Naresuan himself marching toward the border. The Ava command believed that the Siamese army may not only invade Mone but also attack Ava itself.
Momeik, Hsipaw and Hsenwi (1605) The Siamese threat dissipated with the death of Naresuan. At least the Ava command apparently believed so. They decided on to acquire the remaining Near Shan states of
Momeik,
Onbaung (Hsipaw/Thibaw), and Hsenwi, as well as the Hsenwi-backed Bhamo, in the upcoming dry season. The Ava command was most concerned about Hsenwi, the farthest state from Ava, and fronted by Momeik in the west and Hsipaw in the southwest. They expected Bhamo to fall in line once Hsenwi fell. If required, a separate campaign to Bhamo would begin on . The plan was announced on . It shows they expected the Momeik–Hsipaw–Hsenwi campaign to be over by mid-December at the latest. The actual campaign was even shorter. The two-pronged invasion was over in less than a month. The First Army (3000 men, 200 horses, 20 elephants) led by Anaukpetlun marched to Momeik via
Singu while the Second Army (4000 men, 300 horses, 20 elephants) led by Nyaungyan marched to Hsipaw. ==Death==