During the 18th and 19th century B.C.E, the Masai people moved into what is now modern-day Central Kenya from a region north of Lake Rudolf. Although there were not many, they managed to conquer a great amount of Bantu-speaking peoples, due to the fact that they did not put up much of a resistance against the Masai. However, the Nandi peoples managed to oppose the Masai, while the Taveta peoples fled to the forests on the eastern edge of Mount Kilimanjaro, along with the Kikuyu peoples, although they later were forced to leave the land due to the threat of smallpox. An outbreak of either rinderpest or pleuropneumonia greatly affected the Masai's cattle, while an epidemic of smallpox affected the Masais themselves. After the death of the Masai Mbatian, the chief ''laibon'' (medicine man), the Masai split into warring factions. Although Arab traders remained in the area, trade routes were disrupted by the hostile Masai. The first foreigners to successfully get past the Masai were Johann Ludwig Krapf and Johannes Rebmann, two German missionaries who established a mission in Rabai, not too far away from Mombasa.