The Sino-British Joint Declaration is a treaty between the governments of the United Kingdom and China signed in 1984 setting the conditions in which Hong Kong was to be transferred to Chinese control and for the governance of the territory after 1 July 1997. Hong Kong had been a colony of the British Empire since 1842 after the First Opium War and its territory was expanded on two occasions; first in 1860 with the addition of Kowloon Peninsula and Stonecutters Island, and again in 1898 when Britain obtained a 99-year lease for the New Territories. The date of the handover in 1997 marked the end of this lease.