move again, at first westwards into present-day Botswana and then later northwards towards what is now Zambia. He was unable to settle the land there because of the prevalence of tsetse fly which carried diseases fatal to oxen. Mzilikazi therefore travelled again, this time southeastwards into what became known as Matabeleland (situated in the southwest of present-day Zimbabwe) and settled there in 1840 where he reunited with the splinter group led by Gundwane Ndiweni. After his arrival, he organised his followers into a militaristic system with regimental kraals, similar to those of Shaka; under his leadership, the Matabele became strong enough to repel the Boer attacks of 1847–1851 and persuade the government of the South African Republic to sign a peace treaty with Mzilikazi in 1852. Matebele Kingdom While Mzilikazi was generally friendly to European travellers, he remained mindful of the danger that they posed to his kingdom. In later years he refused some visitors access to his realm. The Europeans who met Mzilikazi included Henry Hartley, hunter and explorer; Robert Moffat, missionary; John Mackenzie, missionary; David Hume, explorer and trader; Andrew Smith, medical doctor, ethnologist and zoologist; William Cornwallis Harris, hunter; and the missionary explorer David Livingstone. During the tribe's wanderings north of the Limpopo, Mzilikazi became separated from the bulk of the tribe. They gave him up for dead and hailed his young heir Nkulumane as his successor. However, Mzilikazi reappeared after a traumatic journey through the Zambezi Valley and reasserted control. According to one account, his son and all the chiefs who had chosen him were put to death on his orders. A popular belief is that they were executed by being thrown down a steep cliff on the hill now called Ntabazinduna [hill of the chiefs]. Another account claims that Nkulumane was not killed with the chiefs, but was sent back to the Zulu Kingdom with a sizeable delegation which included warriors. During his journey south, he passed through the Bakwena territory in the northwestern Transvaal, near Rustenburg. At the time the Bakwena were struggling to repel repeated attacks from a neighbouring king, who laid claim to the territory that they occupied. Nkulumane assisted the Bakwena by leading his impi in a battle in which Nkulumane himself killed the neighbouring chief. Following this victory, the Bakwena convinced Nkulumane to settle in their territory, arguing that it would be futile to return to the Zulu Kingdom as