themselves, but preferred to buy them for guns, cloth, jewelry, and other goods. Through their participation, the Luvale became a force to reckon with, and raided nearby tribes to procure slaves for the Ovimbundu. By the mid 19th century, guns were widespread in both Luvale society and culture, and travellers' accounts noted that practically all the major chiefs were also important slave traders. Chiefs Nyakatolo and Kangombe Kayambi were two particular Luvale that became notorious for their involvement in the slave trade. The Luvale also augmented their wealth by exacting payments from caravans, in exchange for passing through their areas uninterrupted. The Luvale would continually expand their domain in search of new raiding targets, coming to clash with the Southern Lunda chieftainships in particular. The slave trade would reach its peak and the 1830s and 1840s, before slowly dying out by the turn of the century. Starting in the 1890s, Luvale slaving parties carried out a series of attacks against the Lunda, which came to be known as "the Wars of Ulamba." In an unprecedented move, the Lunda chief Ishinde appealed to the Barotse's leader, Lewanika, for aid against the Luvale. Lewanika, seeking to consolidate his grip over the region, sent a military contingent against the Luvale. The Luvale's slave raiding activities were only completely stopped by British conquest in the early 20th century. In 1907, the slaves in the part of the Upper Zambezi under British administration were officially freed, but a system of debt slavery continued on a limited scale for the decades. European rule Barotseland and its neighbors were brought under formal British influence with the signing of the Lochner Concession in 1890 between Lewanika and the British South Africa Company (BSAC). Lewanika had made the claim that the Upper Zambezi was under his domain, a valid statement in the eyes of the Barotse, as it was supported by their intervention in the Wars of Ulamba. BSAC, which was anxious to counter Portuguese claims, accepted the claim. Because it was advantageous to the interests of the Barotse and the BSAC, Balovale was henceforth considered to be a part of Barotseland. The Lunda, and especially the Luvale, were vehemently opposed to Barotse influence, and complained vigorously to a succession of District Commissioners that the historical justification used for Barotse rule was mistaken. Nevertheless, colonial administrators continued to support Barotse rule, and this would be reflected in the administration