Mombasa travels to the Swahili Coast and made some mention of the city, although he only stayed one night. He noted that the people of Mombasa were Shãfi'i Muslims, religious people, trustworthy and righteous. Their mosques are made of wood, expertly built. The exact founding date of the city is unknown, but it has a long history. Kenyan school history books place the founding of Mombasa as 900 A.D. It must have been already a prosperous trading town in the 12th century, as the Arab geographer Al Idrisi mentions it in 1151. The oldest stone mosque in Mombasa, Mnara, was built
Mombasa Segeju and went home. This stimulated the Portuguese to take over Mombasa a third time in 1589, and four years later they built Fort Jesus to administer the region. Between Lake Malawi and the Zambezi mouth, Kalonga Mzura made an alliance with the Portuguese in 1608 and fielded 4,000 warriors to help defeat their rival Zimba, who were led by chief Lundi. After the building of Fort Jesus Mombasa was put by the Portuguese under the rule of members of the ruling family of Malindi. In 1631 Dom Jeronimo the ruler of Mombasa slaughtered the Portuguese garrison in the city