How did Hong Kong join china?

Answer 1

It joined it in July 1997, after the lease of the island of Hong Kong and the surrounding HK area ran out, following the 1984 treaty which the UK government agreed with Communist China to lease the islands back.

There was a lavish ceremony and handover procession, and as part of the agreement Hong Kong kept control of most of its law, including capitalist economic system, until 2047. However today China continues to try and destroy civil rights in Hong Kong.

I for one, as a British person, very much miss HK. And the people of HK, they say, miss Britain.