Decapolis (dēkăp`əlĭs) [Gr.,=ten cities], confederacy of 10 ancient cities, all E of the Jordan, except Scythopolis. The others were (according to Pliny) Dion, Pella, Gadara, Hippos, Gerasa, Philadelphia, Damascus, Raphana, and Kanatha. The league was constituted after Pompey's campaign (65 B.C.–62 B.C.) as a protection against the Jews and the Arabian tribes and as a customs union. The Roman governor of Syria exercised general supervision of its affairs, and the cities belonging to the league were liable to Roman military service and taxation.