Africa's ancient historic period includes the rise of Egyptian civilization, the further development of societies outside the Nile River Valley and the interaction between them and civilizations outside of Africa. In the late 7th century North and East Africa were heavily influenced by the spread of Islam. That led to the appearance of new cultures such as those of the Swahili people, and the Mali Empire, whose king, Musa Keita I, became one of the richest and most influential people of the early 14th century. This also led to an increase in the slave trade that had a very bad influence for the development of the whole continent until the 19th century.