text:  The period of calm for Pagan ended in the early <unk> . By then , the Song were on the ropes , and Emperor <unk> Khan , who officially founded the Yuan dynasty on 18 December 1271 , sought to cut off the retreat of Song refugees in all directions . In Pagan 's case , he had ordered the <unk> governor of <unk> to <unk> control of the <unk> , and in January 1271 to send a mission to Pagan to demand tribute . The tribute he demanded was nominal . Given his higher priority <unk> elsewhere , the emperor was not looking to replace the regime at Pagan . At the border , the ruler of the <unk> and <unk> regions submitted to the Mongols . 
  