In contrast to most ethnic groups in Africa, the isolated, low density pastoral nomadic lifestyle left the Ovambo people largely unaffected by the Swahili-Arab and European traders before the 19th century. When Germany established a colony in Namibia in 1884, they left the Ovambo people undisturbed. The Germans focused on the southern and coastal regions. After World War I, Namibia was annexed into the South African administration by the British as the South West Africa province. This brought major changes, with South African plantation, cattle breeding and mining operations entering the Ovamboland. The colonial Portuguese administration in Angola, who had previously focused on their coastal, northern and eastern operations, entered southern Angola to form a border to the expanding South African and British Imperial interests. The Ovambo people launched several armed resistance in the 1920s and 1930s, which were all crushed militarily by the British and Portuguese forces.