The Roman state annexed Dardania by the first century CE. The importance of the area lay in its mining potential ("metalla Dardana") which was heavily exploited in the CE centuries as highlighted by the large mining complex of Municipium Dardanorum and the designation of part of the region as an imperial mining district. Kosovo was part of two provinces, Praevalitana and Dardania. Ulpiana is the most important municipium which developed in Kosovo. It was refounded as "Justiniana Secunda" under Justinian in the 6th century CE.