According to one estimate, between 1967 and 1978 some 1,151 individuals were deported by Israel, including two whole tribes, dispatched into exile en masse from the area of the Jordan Valley in December 1967 and May 1969. To provide legal warrant for these measures, which contravene the Fourth Geneva Convention, Israel applied law 112 going back to the British Mandatory government's Defence (Emergency) Regulations which predated the Geneva Convention by 4 years. These in turn went back to military legislation devised to counteract the Palestinian war of opposition to British occupation and Jewish immigration in 1936-1939.