Gejiu is located on the top of a mountain to the north of the Red River (pinyin Hong He) valley, which flows from Xiangyun, Yunnan, to Vietnam.

In 1889, Mengzi was opened as a treaty port to serve as a gateway for trade between the Qing Government and what was then French Indochina.

In addition to the city's tin mine, which remained the chief product, Gejiu had also become a major producer of lead, and a thriving metallurgical industry has been developed.

Coal for smelting was supplied to the city from nearby Kaiyuan to the north, located on the rail line to Kunming.

Today, Gejiu is a relatively modern prosperous county-level city in Yunnan, with a lakeside setting and with a backdrop of rocky hills.

This accident may well have turned out to be a blessing in disguise for Gejiu, as it provided a nice scenic lake right in the city center.

It is a typical subtropical highland climate (Köppen: Cfb), with a low temperature variation but cold for latitude.

However, minorities such as the Muslim Hui, Dai from the nearby Red River valley, and Hani from the surrounding mountains (see Yuanyang) are also present[citation needed].