Xi (shē) [key] or Xi Jiang shē jyäng, great river of S China, c.1,250 mi (2,010 km) long, rising in E Yunnan prov. and flowing generally E through Guangxi and Guangdong provs. to the South China Sea near Guangzhou; the Kui, Bei, and Dong rivers are its chief tributaries. The Xi flows mainly through narrow, confined valleys. At the junction with the Bei, W of Guangzhou, the Xi forms the vast Pearl River delta (2,890 sq mi/7,485 sq km), consisting of a maze of channels and canals. The densely populated delta is one of China's chief economic areas; agriculture (rice, sugarcane, fruit) predominates. One of China's principal inland waterways, the Xi is navigable for large ships along almost half of its length. It is also called the West River.