southern port city of Martaban (Mottama) by killing its Pagan-appointed governor. Gov. Akhamaman of Pegu also revolted; the king managed to send two small expeditions to Pegu but they both failed. Now, the entire eastern half of Lower Burma (Pegu and Martaban) was in open revolt. Peace negotiations (1285–1287) Ceasefire Given his precarious position, Narathihapate decided to buy time, and sue for peace with the Mongols. In November/December 1285, the king ordered his generals Ananda Pyissi and Maha Bo to enter into ceasefire negotiations. The Mongol commanders at Hanlin, who had organized northern Burma as a protectorate named Zhengmian (), agreed to a ceasefire but insisted on a full submission. They repeated their 1281 demand that the Burmese king send a formal delegation to the emperor. The two sides had reached a tentative agreement by 3 March 1286, which calls for a full submission of the Pagan Empire, and central Burma to be organized as the province of Mianzhong (). After a long deliberation, the king agreed to submit but wanted the Mongol troops to withdraw. In June 1286, he sent an embassy led by Shin Ditha Pamauk, a learned monk, to the emperor's court. Treaty of Beijing In January 1287, the embassy arrived at Beijing, and was received by the Yuan emperor. The Burmese delegation formally acknowledged Mongol suzerainty of their kingdom, and agreed to pay annual tribute tied to the agricultural output of the country. (Indeed, the tribute was no longer nominal.) In exchange, the emperor agreed to withdraw his troops. For the emperor, the Burma campaign was the only bright spot; his other Southeast Asian expeditions had gone badly. He did not want to invest more troops pacify the rest of the kingdom. He preferred a vassal ruler. The Burmese embassy arrived back at Hlegya in May 1287, and reported the terms to the king. Breakdown 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, King Narathihapate 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. Mongol last push for Pagan (1287)