1800: Prior to the arrival of the French, the Lao Kingdom of Lan Na was under the suzerainty of Siam (now Thailand) in the late 18th century. As part of the historic Southern Silk Road, various caravan and river-based routes along the upper Mekong River linked Southern Yunnan’s Sip Song Pan Na with Lan Na in Northern Siam.

 

1887: Following the successful French colonial acquisition of Tonkin and Annam (parts of modern-day Vietnam) in 1884 and the establishment of the Indochinese Union in 1887, the French began to plan for further expansion toward the Mekong River as a potential trade route to China.

 

1893: The Franco–Siamese War of 1893 was ended by the Treaty of Bangkok. Under the 1893 treaty, Siam was obliged to relinquish its claim to the Shan region of Northeastern Burma to the British and cede the Lao principalities on the eastern bank of the Mekong to the French.

 

1895: Known for its numerous salt wells, Boten was an important salt producer and a well-established caravan stop along a major trade route. Preoccupied with Japanese aggression during the First Sino–Japanese War (1894–1895), Qing China signed an agreement with the French, handing control over Boten and granting preferential terms for French goods entering Yunnan.

 

1913: The Yunnan provincial government of the newly established Republic of China (ROC) sent troops to oust the rebels in Sip Song Pan Na.

 

1927: Zhenyue County, which means “pacifying Indochina,” was established along the southernmost border of the ROC bordering French Indochina. It was later renamed Mengla County.

 

1939: Mountainous and flood-prone Laos was considered by the French as an economically unviable colonial backwater. By the late 1930s, the socioeconomic development of the French protectorate of Laos, particularly its northern regions, lagged behind that of the rest of Indochina.

 

1950: Sip Song Pan Na experienced a boom in rubber production when the central government of the newly established People’s Republic of China (PRC) designated natural rubber as a strategic industrial product during the Korean War (1950–1953) in response to the US trade embargo.

 

1953: The Kingdom of Laos proclaimed independence. On the Chinese side, the native chieftain system was abolished, and the Xishuangbanna Dai Autonomous Region was established. The border between the PRC and Myanmar and Laos remained relatively closed owing to regional tension.

​

1993: The Greater Mekong Subregion Economic Cooperation Program was established in 1992. An agreement was reached between China and Laos to establish Mohan Port in Mengla County, China, and Boten Port in Luang Namtha Province, Laos.

 

2001: The Mohan Border Trade Zone was established. Boten, which is located at the China–Laos border, experienced a boom in casinos in the early 2000s and was established as a land concession called Golden Boten City (GBC) in 2007, which was leased by a Hong Kong-registered company.

 

2010: GBC rapidly declined after a Chinese crackdown on over-the-border gambling. A memorandum of understanding was signed between Laos and China for the China–Laos Railway project.

 

2015: The Mengla Key Development and Opening Pilot Zone was established in China. China and Laos signed an agreement on the development of the Mohan–Boten Economic Cooperation Zone.

 

2016: Boten experienced rapid transformation after GBC was acquired from its original owners by a Yunnan-based company, which established the Boten SEZ under a 90-year lease agreement.

 

2017: Construction of the China–Laos Railway formally began in 2016, and the Chinese section of the Kunming–Bangkok Expressway from Kunming to Mohan was completed in 2017. Completion of the China­–Laos Railway is expected in 2021.