Slavs founded several settlements in the Bucharest region, as pointed out by the Slavic names of Ilfov (from elha - "alder"), Colentina, Snagov, Glina, Chiajna etc. According to some researches, the Slavic population was already assimilated before the end of the Dark Ages. According to some researches, the area was part of the First Bulgarian Empire between 681 and c.1000. While maintaining commercial links with the Byzantine Empire (as attested by the excavations of 9th-12th century Byzantine coins at various locations), the area was subject to the successive invasions of Pechenegs and Cumans and conquered by the Mongols during the 1241 invasion of Europe. It was probably later disputed between the Magyars and Second Bulgarian Empire.
According to a legend first attested in the 19th century, the city was founded by a shepherd named Bucur (or, alternatively, a boyar of that same name). Like most of the older cities in Muntenia, its foundation has also been ascribed to the legendary Wallachian prince Radu Negru (in stories first recorded in the 16th century). The theory identifying Bucharest with a "Dâmbovi?a citadel" and pârc?lab mentioned in connection with Vladislav I of Wallachia (in the 1370s) is contradicted by archaeology, which has shown that the area was virtually uninhabited during the 14th century.