The Massylii or Maesulians were a Berber federation in eastern Numidia, which was formed by an amalgamation of smaller tribes during the 4th century BC. They were ruled by a king. On their loosely defined western frontier were the powerful Masaesyli. To their east lay the territory of the rich and powerful Carthaginian Republic. Their relationship to Carthage resembled that of a protectorate. Carthage maintained its dominance over the Massylii by skillful diplomatic manoeuvering, playing off local tribal and kingdom rivalries. The principal towns of the Massylii were Cirta, Tébessa and Thugga in Algeria and Tunisia.