Foederati

Foederatus (/ˌfɛdəˈreɪtəs/ in English; pl. foederati /ˌfɛdəˈreɪtaɪ/) was any one of several outlying nations to which ancient Rome provided benefits in exchange for military assistance. The term was also used, especially under the Roman Empire for groups of "barbarian" mercenaries of various sizes, who were typically allowed to settle within the Empire.