The earliest known human settlements in what is now the Democratic Republic of the Congo have been dated back to the Middle Stone Age, approximately 90,000 years ago. The first real states, such as the Kongo, the Lunda, the Luba and Kuba, appeared south of the equatorial forest on the savannah from the 14th century onwards.
The Kingdom of Kongo controlled much of western and central Africa including what is now the western portion of the DR Congo between the 14th and the early 19th centuries. At its peak it had many as 500,000 people, and its capital was known as Mbanza-Kongo (south of Matadi, in modern-day Angola). In the late 15th century, Portuguese sailors arrived in the Kingdom of Kongo, and this led to a period of great prosperity and consolidation, with the king's power being founded on Portuguese trade. King Afonso I (1506–1543) had raids carried out on neighboring districts in response to Portuguese requests for slaves. After his death, the kingdom underwent a deep crisis.