China once leased Hong Kong to Great Britain for 99 years
Hong Kong was leased to Great Britain by China in 1898 for 99 years. On December 19, 1984, Britain signed a pact with China, agreeing to return Hong Kong when the lease ended in 1997. Meanwhile, China promised to implement the "One Country, Two Systems" policy wherein Hong Kong would maintain a separate political and economic system for 50 years.