During the Laotian Civil War, Yao tribes of Laos had a good relationship with U.S. forces and were dubbed to be an "efficient friendly force". They fought in favour of government against the communists.This relationship caused the new communist Laotian government to target Yao tribal groups for revenge once the war was over. This triggered further immigration into Thailand, where the tribes would be put into camps along the Thailand-Laos border.