Ceasefire negotiations began in 1285 , and ended with Narathihapate finally agreeing to submit in June 1286 . The Burmese embassy , received by the emperor in Beijing in January 1287 , agreed to a treaty that acknowledged the suzerainty of the Yuan dynasty or the Mongol Empire over the Pagan Empire and annual payments in taxes to the Yunnan government in exchange for the evacuation of Mongol troops from northern Burma . But the treaty never really took no effect as Narathihapate was assassinated in July 1287 , and no authority who could honor the treaty emerged . The Mongol command at Yunnan now deemed the imperial order to withdraw void , and ordered an invasion of central Burma . They may not have reached Pagan , and even if they did , after having suffered heavy casualties , they returned to Tagaung .