Gejiu is a county-level city and the capital of Honghe prefecture, Yunnan Province, China, and has 136,000 inhabitants (ranked 5th largest city in Yunnan). It is the site of the country's largest tin deposits and its main industry is mining.
Gejiu is located on top of a mountain to the north of the Red River (pinyin Hong He) valley, which flows from Tibet to Vietnam. To the south-west in this valley is Nansha, which lies directly below the town of Yuanyang. To the north-west lies Jianshui, and to the north Jijie. Mengzi lies 12 miles to the west.