Mbanza-Kongo (formerly called Nkumba a Ngudi, Mongo wa Kaila and Kongo dia Ngunga [1][2]) was founded by the first manikongo, Lukeni, at a junction of major trade routes.[3]: 202  The Kingdom of Kongo at its peak reached from southern Africa's Atlantic coast to the Nkisi River. The Manikongo was chosen by clan leaders to rule some 300 mi2, an area that today is part of several countries. The Portuguese who first reached it in 1491 travelled ten days to get there from the mouth of the Congo River.[4]

 Portuguese coat of arms of São Salvador

The earliest documented kings referred to their city in their correspondence as "the city of Congo" (cidade do Congo), and the name of the city as São Salvador appears for the first time in the letters of Álvaro I of Kongo (1568–1587) and was carried on by his successors.

When the Portuguese arrived in Kongo, Mbanza Kongo was already a large town, perhaps the largest in sub-equatorial Africa, and a letter from the Portuguese ambassador to Lisbon compared the size of the city (inside the inner walls) to the Portuguese town of Évora.[5]

By the 1550s Mbanza-Kongo hosted a community of Portuguese traders and Jesuit missionaries who conspired together in an attempted overthrow of the manikongo Diogo I Nkumbi a Mpudi.[3]: 217 

In 1568 the manikongo Alvaro I was driven from Mbanza-Kongo by the invading Jagas, who sacked the city. Alvaro managed to reclaim the capital with Portuguese military help, but had to yield Luanda, source of the nzimbu currency used in the kingdom, to them in payment.[3]: 218 

During the reign of Afonso II, stone buildings were added, including a palace and several churches. Mbanza-Kongo grew substantially as the kingdom of Kongo expanded and grew, and an ecclesiastical statement of the 1630s related that 4,000-5,000 baptisms were performed in the city and its immediate hinterland (presumably the valleys that surround it), which is consistent with an overall population of 100,000 people. Of these, perhaps 30,000 lived on the mountain and the remainder in the valleys around the city. Among its important buildings were some twelve churches, including São Salvador, as well as private chapels and oratories and an impressive two-story royal palace, the only such building in all of Kongo, according to visitor Giovanni Francesco da Roma (1648).[citation needed]

The city was sacked several times during the civil wars that followed the Battle of Mbwila (or Ulanga) in 1665, and was abandoned in 1678. It was reoccupied in 1705 by Dona Beatriz Kimpa Vita's followers and restored as Kongo's capital by King Pedro IV of Kongo in 1709.[3]: 256  It was never again depopulated though its population fluctuated substantially during the eighteenth and nineteenth century.

The name was changed back to "City of Kongo" (Mbanza Kongo) shortly after Angolan independence.