Jewish migration to Palestine and widespread Jewish land purchases from feudal landlords contributed to landlessness among Palestinian Arabs, fueling unrest. Riots erupted in Palestine in 1920, 1921 and 1929, in which both Jews and Arabs were killed. Britain was responsible for the Palestinian mandate and, after the Balfour Declaration, it supported Jewish immigration in principle. But, in response to the violent events noted above, the Peel Commission published a report proposing new provisions and restrictions in Palestine.