History of Hong Kong

Hong Kong (1800s–1930s) was a period largely dominated by the British Empire. After invading the territory in 19th century during the Opium War, the British gained land in a series of unequal treaties. Hong Kong became one of the first parts of East Asia to undergo industrialisation.

https://en.m.wikipedia.org/wiki/History_of_Hong_Kong
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British Hong Kong denotes the period during which Hong Kong was governed as a colony and British Dependent Territory of the United Kingdom. Excluding the Japanese occupation during the Second World War, Hong Kong was under British rule from 1841 to 1997.

The colonial period began with the occupation of Hong Kong Island in 1841 during the First Opium War. The island was ceded by Qing China in the aftermath of the war in 1842 and established as a Crown colony in 1843.

The colony expanded to the Kowloon Peninsula in 1860 after the Second Opium War and was further extended when Britain obtained a 99-year lease of the New Territories in 1898.

Although Hong Kong Island and Kowloon were ceded in perpetuity, the leased area, which comprised over 90 per cent of the territory, had such a vital role in the economy that Britain agreed to transfer the entire colony to China upon the expiration of that lease in 1997.

The transfer has been considered by many as marking the end of the British Empire.

https://en.m.wikipedia.org/wiki/British_Hong_Kong