There are 24 thousands-year ancient counties in Yunnan, and Mengzi is one of them. It played a very important role in the Yunnan modern and contemporary history.Since 109 B.C. (the Western Han Dynasty period), Mengzi was original called Bengu which was belonged to the Yizhou County during that time. And in 1276 A.D., it was renamed as Mengzi and kept the name till now. 

When the War between China and France (1883 - 1885) was finished, Guangxu Emperor (Qing Dynasty) points Longzhou in Guangxi Province and Mengzi in Yunnan Province as two main trade ports to deal with the foreign trades.

Mengzi was once the largest Yunnan trade port to deal with the external trade. During that moment, more the 80% import and export trade was operated in Mengzi port. In 1886, a French convention chose Mengzi to be the center of trade in Yunnan province for importing and exporting goods via Tongking in Vietnam. Facilities for this opened 2 years later.

There were many “Yunnan firsts” in Mengzi, including:

► The first custom in Yunnan

► The first telegraph office in Yunnan

► The first post office in Yunnan

► The first foreign bank in Yunnan

► The first private railway in Yunnan

► The first foreign-funded enterprise in Yunnan

► The first consulate in Yunnan

► The first thermal power station in Yunnan

In 1992 Nov, Mengzi County was listed as the Yunnan provincial economy developing district. In Dec the same year, it was upgraded as the national opening-up county. And finally in 2003 Jan, Mengzi County became the political center of Honghe Hani and Yi Autonomous Prefecture

The significant of Mengman Ancient Road (Mengman Gu Dao)

Mengan Ancient Road (the route connecting Mengzi City and the Manhao Area of Gejiu City) is the ancient transporting route between Southern Yunnan and Vietnam. The road reached Vietnam via Manhao area, totally length was 210 km. The part in Mengzi was 60km.

With a 1.2 to 2.2 width, the Mengman Ancient Road was built by stones. At present, the preserved parts are Liangshuijing, Lengquan, Shuitian, Yaotou, and Manhao, etc. 

During the Guangxu Emperor period, the horse caravans were in the peak time in Mengzi. They travelled between Yunnan and Vietnam on this road frequently. So till now, there are still many horse footprints left on the route.

In 2012 it became apparent that several sets of fossil hominins from Maludong near Mengzi City (some of them already in museum collections) might potentially belong to a new species of homo sapiens although only 11-14K years old. These are provisionally known as the Red Deer Cave people.

In the 19th century, Mengzi was a trading centre for commerce between the interior of Yunnan and the Hanoi-Haiphong area of Vietnam.

In 1886, a French convention chose Mengzi to be the center of trade in Yunnan province for importing and exporting goods via Tongking in Vietnam. Facilities for this opened 2 years later.

Communications were inconvenient: goods 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. Despite these difficulties, Mengzi was an important port of entry into both Yunnan and western Guizhou provinces, and in 1889 it was opened to foreign trade as a treaty port. Most of this foreign trade was in tin and opium. Its main exports were tin and  opium, and the main imports were mostly textiles (primarily cotton) and tobacco.

As a trading center, the city gradually began to lose its importance beginning from the early 20th century. The importance of Mengzi was ended by the construction of the French railway from Haiphong to Kunming (the Yunnan provincial capital) in 1906–10. This railway bypassed Mengzi, but in 1915 a branch line was built via the town to the Gejiu tin mines. 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.

Gejiu became a county in 1913, and a city in 1951. With the improvement of communications and transportation between cities of Gejiu and Kaiyuan and the other counties nearby, plus the development of trade between southwestern China and the countries of Southeast Asia, Mengzi's ties have increasingly strengthened with Gejiu and Kaiyuan. The whole area has become a border economic centre. In addition to tin, the county's natural resources include coal, manganese, lead, zinc, and antimony.

When Japanese troops drove Beijing and Tianjin university professors, students, and administrators out of those cities, and then later out of Changsha as well, the academics made their own long march to Yunnan Province. They first established themselves in Mengzi, but after a year or so moved on to the provincial capital, Kunming. This was Lianda, or the Southwest Associated Universities.

Recently, the prefectural government has moved from nearby Gejiu to Mengzi. New wealthy suburbs and large government offices have sprung up as a result, but much of the poverty remains, creating a large wealth gap within the city.