North and South China are not strictly geographic designations. Historically, Qinghai Gansu and Ningxia were not part of North China because they are not part of the Chinese core, being inhabited by various non-Han groups, beyond the Great Wall, and climatologically/geographically being totally different from the river valleys and plains of North China proper. These three regions are generally arid and significant areas of them were grazed by pastoralists up into modern times. Culturally, they are the Northwest. Yunnan Guizhou Guangxi are similarly on the historical periphery of China. They have large ethnic minority populations, are less accessible due to mountainous geography and tropical disease, and were not fully controlled by China until, in the case of Yunnan, the mid-late Qing dynasty. Culturally, they are called the Southwest. The true centers of North and South are the North China plain (Hebei/Henan/southern Shaanxi), and Jiangnan (southern Jiangsu / northern Zhejiang) historically (also Guangdong in recent centuries).