Waves of mass migrations from Hong Kong villagers exercised their right of abode in the United Kingdom and left for Europe. In 1967, a series of large-scale riots erupted in Hong Kong, causing social instability. These events led some of the richer Hong Kong residents to move abroad. Emigration took place to countries in Southeast Asia, South Africa or South American countries. This wave did not come to a rest until the mid-1970s. On the 19th of December 1984, the People's Republic of China and the United Kingdom signed the "Sino-British Joint Declaration", validated the 1997 transfer of sovereignty over Hong Kong to China. The declaration prompted
British nationality law and Hong Kong Kong began to fear for their future post-1997. Emigration was rampant and a brain-drain was beginning to affect the economy of Hong Kong. To stem the drain, people urged the British government to grant full British citizenship to all Hong Kong BDTCs – but this request was never accepted. However, the British did agree to creating the British Nationality Selection Scheme, which granted to a select 50,000 people and their families the ability to obtain full British citizenship without having to fulfill the ordinary requirements, under the "British Nationality (Hong Kong) Act, 1990". Under the act, the Home Secretary was