 Complete the following phrase:  In 937, Duan Siping overthrew the Nanzhao and established the Dali Kingdom. The kingdom was conquered by the Mongol Empire in 1253 after Dali King Duan Xingzhi defected to the Mongols. The Duans incorporated into the Mongol dominion as Maharajas of the new province. The Mongolian prince sent to administer the region with them was killed. In 1273, Kublai Khan reformed the province and appointed the semu Ajall Shams al-Din Omar as its governor. The Yun Province during the Yuan dynasty included significant portions of Upper Burma after the 