Luzhou was incorporated into the Ba state early in the Shang and Zhou period, in the 11th century BC. In 316 BC, during the Qin Dynasty (221 BC-208 BC), Emperor Huiwen established Ba prefecture, which included most of Luzhou, after he conquered Ba and Shu. During the period of Western Han Dynasty (206 BC-AD 23), a county of Jiangyang county was set up in what is the current Jiangyang district, where the Tuo River and Yangtze River emerged. The Song Dynasty (196-1127) was an important period in Luzhou's history. It was known as the natural granary of southern Shu as the wine-making and salt-refining industries expanded. The method to decoct salt with natural gas was discovered at that time, according to ancient literature. In the Yuan Dynasty, 1279-1368, Luzhou remained an important place for the wine-making, salt-refinery and tea-making industry and trade.