Arab opposition increased as the 1917 Balfour Declaration and the wave of Jewish settlers to Palestine began to tilt the demographic balance of the area. Arabs responded with bloody riots in Jerusalem in 1920, Jaffa in 1921 and in Hebron in 1929. In the late 1930s, Arab–Jewish violence became virtually constant; the 1936–39 Arab revolt in Palestine is also known as the "Great Uprising" in Palestinian historiography.