Ratiaria (or: Raetiaria, Retiaria, Reciaria, Razaria; Bulgarian: Рациария; Greek: Ραζαρία μητρόπολις; later named Colonia Ulpia Traiana Ratiaria) was a city founded by Moesi, a Daco-Thracian tribe, in 4th century BC, along the river Danube. The city had a gold mine in the vicinity, which was exploited by the Thracians.