Hong Kong became a British colony in 1842 after China and Great Britain had led a war on opium trade. At that time Hong Kong had already become an important trading post. At first the British only occupied Hong Kong Island; later on it expanded its rule to Kowloon Peninsula and the New Territories, which it leased for 99 years.
In 1984 The British and Chinese signed an agreement that would give Hong Kong back to the Chinese. In 1997 the former British colony became a special administrative region of China. This had become necessary because Hong Kong has a different political system than China. It is a city state that governs itself. The Chinese, however, agreed to give Hong Kong special autonomy and respect its status until 2047.
March with a British Hong Kong flag on July 1, 1997
Image: Silvermetals CC BY-SA 3.0