The Qin Dynasty (221BC-206BC) first established the counties and shires of this area. Its territory was initially formed by the ascription of five counties from Yunnan and Sichuan provinces. In 1965, Panzhihua was renamed from a special zone into Dukou City, and gained its present name in 1987. It is the only city in China having a name of a flower, and its economy relies almost entirely on its giant mine, one of the biggest in China. The latter makes it a very polluted city, where the air condition is quite poor. While most of cities in North China are locked in freezing winter, Panzhihua maintains a sunny climate. In fact more than ninety-four percent of the winter days are sunny.