Following the conquest of Dali in 1253, the former ruling Duan dynasty were appointed as governors-general, recognized as imperial officials by the Yuan, Ming, and Qing-era governments, principally in the province of Yunnan. Succession for the Yuan dynasty, however, was an intractable problem, later causing much strife and internal struggle. This emerged as early as the end of Kublai's reign. Kublai originally named his eldest son, Zhenjin, as the Crown Prince, but he died before Kublai in 1285. Thus, Zhenjin's third son, with the support of his mother Kökejin and the minister Bayan, succeeded the throne and ruled as Temür Khan, or Emperor Chengzong, from 1294 to 1307. Temür Khan decided to maintain and continue much of the work begun by his grandfather. He also made peace with the western Mongol khanates as well as neighboring countries such as Vietnam, which recognized his nominal suzerainty and paid tributes for a few decades. However, the corruption in the Yuan dynasty began during the reign of Temür Khan.