But the agreement broke down a month later . In late June , the defeated king and his small retinue left their temporary capital for Pagan . But on 1 July 1287 , the king was captured en route and assassinated by his second son Thihathu , the Viceroy of Prome . Anarchy ensued . Each region in the country which had not revolted broke away . No successor to Narathihapate , who could honor and enforce the terms of the treaty of Beijing , emerged . Indeed , a king would not emerge until May 1289 .