river valleys were densely populated. Around 1800, in the second half of the rule of the Luba Emperor Ilunga Sungu, Luba forces launched raids over the Lualaba that at one point reached as far as Kalemie. Some of the Luba settled in the region, and the people around Kalemie were subject to the Luba in the following reigns of Kumwimbe Ngombe and Ilunga Kabale. The Luba evolved the concept of the "fire king" to rule the peripheral areas of their empire such as the Luvua-Lukuga corridor, with the local ruler being a near-equal of the Luba emperor, sending only occasional tributes. The bamdudye and bakasandji secret societies were introduced into the area, providing genesis myths that helped legitimize the fire kings' position. These myths had been adopted and adapted by the Holoholo people of Kalemie by the late nineteenth century. The Hemba state of Kyombo Mkubwa became the main client state of the Luba Empire. However, by the time Europeans started to penetrate the region, Msiri's son Simbi, advancing from the south and forming alliances with the Hemba rulers against incursions from Tippu Tip, had detached Kyombo Mkubwa from the Luba heartland. European contacts Around 1871 David Livingstone noticed the break in the hills through which the "Logumba" passed, and suggested that the river might be an outlet of Lake Tanganyika, and that there could be other outlets further north. Verney Lovett Cameron reached the river at the point where it left the lake in May 1874 on his journey across Africa from east to west. He confirmed that it was the only outlet of Lake Tanganyika, but was unable to get a guide to accompany him down the river to verify that it flowed into the Lualaba. In 1876 Henry Morton Stanley visited the lake. When he arrived, the lake level was low and he described the Lukuga as no more than a large creek extending westward for a great distance. However, he agreed that as the lake level rose the Lukuga would act as an outlet. It seems that a sandbar had formed across the river mouth, and the river had silted behind the bar. In 1879 Joseph Thomson came to Kasenge from Pambete, travelling through very rough country. He found that the Lukuga creek was a large and fast-flowing river. He followed the course of the river for a few days, but hostile inhabitants of the region