Mengzi (Chinese: 蒙自; pinyin: Méngzì; Hani: Maoqziif Siif) is a city in the southeast of Yunnan Province, China.

[3] It is situated in the centre of a fertile valley basin on the Yunnan-Guizhou Plateau[2] 1,310 metres (4,300 ft) above the sea level and was home to about 590,300 inhabitants as of 2021 census.

The history of Mengzi can be traced back to Western Han dynasty when Bengu County (贲古县) was founded (109 B.C.

In 1886, following the war between France and the Qing China, a series of treaties designated Mengzi as a trade port in Yunnan province for the import and export of goods via Tonkin, currently the Northern Vietnam.

[14] Communications were inconvenient: goods from Hanoi or Haiphong were shipped to Hekou on the Vietnamese border by junk, transferred by small craft to Manhao, and then taken 60 km (37 mi) by pack animal to Mengzi.

Apart from a brief respite during the early days of World War II, the town of Mengzi has, nevertheless, steadily declined in importance ever since.

When the Japanese invaded Beijing and Tianjin in the late 1930s, university professors, students, and administrators there were forced to leave and travel south to Changsha.

In 2012, 11-14 thousand year old early human bones from Maludong near Mengzi City (some of them already in museum collections) were reported.

Recent policy developments have promoted economic growth, leading to substantial changes in the local industry structure and employment landscape.

It is home to numerous historic sites, though many of its splendid structures were damaged or destroyed primarily during the Taiping Rebellion[2][23] and the Cultural Revolution in 1960s.