Relations between the Ayutthaya and Lan Na had worsened since the Ayutthayan support of Thau Choi's rebellion.
In 1451, Yuttitthira, a noble of the Kingdom of Sukhothai who had conflicts with Borommatrailokkanat of Ayutthaya, had given himself to Tilokaraj.
Yuttitthira urged Borommatrailokkanat to invade Phitsanulok, igniting the Ayutthaya-Lan Na War over the Upper Chao Phraya valley (the Kingdom of Sukhothai).
In 1460, the governor of Chaliang had surrendered to Tilokaraj.
Borommatrailokkanat now uses a new strategy and concentrates on the wars with Lanna by moving the capital to Phitsanulok.
Lan Na suffers setbacks and Tilokaraj eventually sues for peace in 1475.
