Muslims, and styled themselves sultans. The conversions were not always sincere, but some took the religion very seriously and abstained from alcohol, fasted during Ramadan, prayed and adopted Arabic dress. Charles de la Kethulle, who spent two years in the Zande town of Rafaï, wrote in an 1895 article Le sultanat de Rafaï (Le Congo illustré) that almost all the inhabitants could speak Arabic, including the sultan, chiefs and soldiers. The first Europeans to reach the Uele region were the German botanist and ethnologist Georg August Schweinfurth, who discovered the Uele River in 1870, and the Italian Giovanni Miani. In 1871 Wilhelm Junker (1840–1892), a Russian explorer of German origins, explored the Bomu-Uele region thoroughly. These visitors entered from the north or the east rather than the Congo River. In the 1870s the Egyptians decided to strengthen their control of the Bahr al-Ghazal and of the slave and ivory traders operating from there. Around 1880 many Azande chiefs placed themselves at the disposal of the Egyptians, who were represented by Europeans such as Frank Lupton and Romolo Gessi, in part to fight the slavers. The uprising of Muhammad Ahmad, the self-proclaimed Mahdi, against the Egyptian government in 1881 weakened the influence of the Arabs. Congo Free State Exploration By 1896 King Leopold II of Belgium was becoming concerned that instability in the Bahr al-Ghazal would affect his Congo Free State, and that Sudanese slavers would penetrate further south and join up with the Arab and Swahili traders at Stanley Falls. In January 1888 Alphonse van Gèle explored the Bomu River and part of the Uele river. Leopold's decree of 1 August 1888 divided the Congo Free State into eleven districts, including Aruwimi-Uele with its headquarters in Basoko. Vangèle was instructed to explore the Ubangi River in 1889 and claim land for Leopold II. He was also told to "exploit the ivory of the state domain", and his journal includes many details of tusks he bought or was given by chiefs along the Ubangi, M'bomu and Uele rivers. He had obtained twelve tons of ivory by September 1890. Jérôme Becker met Sultan Djabir at Basoko in December 1889, and in January 1890 reached Jabir's sultanate. In 1890 the Belgian officers Léon Roget and Jules Alexandre Milz travelled up the Itimbiri River from Bumba, then up the Likati River, reached the Uele River in the region of Djabir and descended it almost