Hunan is the native place of world dark tea and the ancestor of China dark tea. More than one thousand years ago, Hunan dark tea was widely spread in the world. It grows at the northern section of the Xuefeng Mountains and the inner side of the Wuling Mountains, which benefit from favorable soil, distinct four seasons, plentiful rainfall, abundant sunshine, warm and moist climate (annual average sunshine time of 1,339 hours and annual average temperature of 16.2oC). The exploration data shows that the crustal movement which happened 600 million years ago made the Xuefeng Mountains become an area gathering the most tillites in the world. In this area, the reserves of tillites account for 85% of the total reserves of the world (in South Africa, it accounts for