Be that as it may, Ramesuan was born at a time when the Kingdom of Sukhothai was increasingly tied to Ayutthaya, being under its suzerainty since 1412. When King Maha Thammaracha IV (Borommapan) of Sukhothai died in 1438, Borommaracha II of Ayutthaya annexed Sukhothai and installed his own son, then seven year old Prince Ramesuan, as viceroy "(uparaja)" of Sukhothai. When Ramesuan was 15 years old, the king sent him to Phitsanulok (which had replaced the city of Sukhothai as capital around 1430) to rule the former territories of Sukhothai which were now known as the "northern cities" "(Mueang Nuea)" and increase the control of the ruling family over them.