 Complete the following phrase:  Kokang had been historically part of China for several centuries and is still claimed by the Republic of China to this day, but was largely left alone by successive governments due to its remote location. The region formed a de facto buffer zone between Yun province and the Shan States. The Yang clan, originally Ming loyalists from Nanjing, consolidated the area into a single polity. In 1840, the Yun governor granted the Yang clan the hereditary rights as a vassal of the Qing dynasty. After the 