Tian Shui is a traditionally crafted Sheng Puer made from old growth Assamica tea trees from Menghai County in Yunnan, China.
https://sevencups.com/shop/tian-shui-...
Because of this old growth material and skilled processing, this tea possess very little astringency and a light sweetness that gives it it's name. In this video Santos goes more in depth on the cultivar, picking, and processing that all contribute to this high end Sheng Puer's smooth and floral flavor.