In 1510, he founded Ketumati, the present-day Toungoo, complete with fortified walls. On 16 October 1510 (Full moon of Tazaungmon 872 ME) Nyo formally announced Toungoo's independence. At his coronation ceremony on 11 April 1511, he was crowned king with the regnal title of Maha Thiri Zeya Thura Dhamma Yaza Dipadi. Ava was in no position to contest the decision, as it had more pressing problems with the Shan raids from the north. At any rate, the announcement was a mere formality. Toungoo had been de facto independent since 1501. After the formal declaration of independence, Nyo largely stayed out of the endemic warfare between Ava and the Confederation of Shan States that consumed much of Upper Burma between 1501 and 1527. When Ava was on the ropes, he did move up his forward base to Yamethin and Taungdwingyi, former Ava territories, on 15 March 1523 (New Moon of Tabaung 884 ME). Ava responded by unsuccessfully laying siege to Toungoo for a month in April–May 1525. Otherwise, the kingdom was largely peaceful.