Transfer of sovereignty over Macau

The transfer of sovereignty of Macau from the Portuguese Republic to the People's Republic of China (PRC) occurred on 20 December 1999. Macau was settled and governed by Portuguese merchants in 1535, during the Ming Dynasty (1368–1644 AD). Portugal's involvement in the region was formally recognized by the Qing in 1749. The Portuguese Governor, emboldened by the First Opium War and the Treaty of Nanking, attempted to annex the territory, expelling Qing authorities in 1846, but was assassinated. After the Second Opium War, the Portuguese government, along with a British representative, signed the Sino-Portuguese Treaty of Peking that gave Portugal sovereignty over Macau, on the condition that Portugal would cooperate in efforts to end the smuggling of opium.

After the founding of the People's Republic of China in 1949, and the transfer of China's seat to the PRC at the United Nations in 1971, foreign minister Huang Hua appealed to the UN Special Committee on Decolonization to remove Macau (and Hong Kong) from its list of colonies, preferring bilateral negotiations ending in a return of the territory, rather than the expected independence outcome. The authoritarian right-wing government of Portugal was expelled by the Carnation Revolution, a coup that occurred in 1974. Within one year, the government of Portugal withdrew troops from Macau, withdrew recognition of the Republic of China in favour of the People's Republic, and began negotiations for the return of Macau. Four conferences from June 1986 to March 1987 resulted in a Sino-Portuguese Joint Declaration on 13 April 1987 and the transfer of sovereignty on 20 December 1999. Macau is granted a high level of autonomy and the retention of its legal system by the Macau Basic Law.

...
Wikipedia