Tonga oral history is local history of no great time depth. Archaeological sites on the southern plateau associated with the arrival of the Tonga from the northwest date from the twelfth century A . D . Although they were shifting cultivators who had cattle, they also relied on game and fish. Their crafts included pottery and ironwork; a few scraps of copper remain. There is little evidence of differences in status or of long-distance trade. Sites in northern Gwembe from much the same period have richer assemblages and may not have been Tonga sites. Finds from Ingombe Ilede indicate trade contacts with the Indian Ocean. Some fourteenth- and fifteenth-century graves contained trade beads and worked gold, copper, and bronze. Ingombe Ilede may have been an outpost of one of the Shona kingdoms. Shona speakers still live nearby. In the eighteenth and nineteenth centuries northern Gwembe was visited by Portuguese and Chikunda from Mozambique, who first sought ivory and slaves, and then settled. In general, the nineteenth century was a time of turmoil: Toka country was occupied for a few years by Makololo from southern Africa; in the last half of the century, Lozi raiders from the Upper Zambezi and Ndebele raiders from Zimbabwe harassed all of Tonga country, and the Lozi established hegemony among the Toka. In the 1890s the British South Africa Company had little difficulty in annexing Tonga country and administering it as part of the newly created Northern Rhodesia that, in 1923, was handed over to the British Colonial Office. Early administrators organized the country into districts and created a skeletal administration based on appointed village headmen. These headmen were grouped into chieftaincies under appointed chiefs, who were responsible to a district administrator. Much land was taken for European settlement. After 1923, native reserves were set aside and allocated to the three divisions into which Tonga were by then grouped, under councils called the Plateau Tonga, the Toka-Leya, and the Gwembe Tonga native authorities. Missions arrived at the beginning of the twentieth century. They established schools and, on the plateau, provided instruction in plow agriculture. The Plateau Tonga developed a cash-crop economy by the 1930s; the Toka, with poorer soils, and the Gwembe Tonga, cut off by the escarpment, continued to work as labor migrants, usually in Zimbabwe, until after Zambian independence in 1964. Independence removed restrictions on African access to employment and the use of lands reserved for European development.