The Kongo Kingdom (1400–1888) was a quasi-imperial state as is evident by the number of people and kingdoms that paid it tribute. If not for the large amount of text written by the EssiKongo that repeatedly called themselves a kingdom, they would be listed as the "Kongo Empire". The Luba Empire (1585–1885) arose in the marshy grasslands of the Upemba Depression in what is now southern Democratic Republic of Congo.