The title was used even after the region fell under the dominion of Rome unto the early [[Roman Empire]], to refer to rulers of vassal kingdoms who did not rise to the level of [[king]]s. The Romans used the Latin terms ''natio'' and ''gens'' for a people as a genetic and cultural entity, regardless of political statehood.
The best-known is probably Herod Archelaus, son of [[Herod the Great]], who was ethnarch of [[Samaria]], [[Judea]] (Biblical Judah), and Idumea (Biblical [[Edom]]), from the death of his father in 4 B.C. to A.D. 6. The territory was known as the Tetrarchy (''ruler of a quarter'') of Judea. His brother Philip was assigned the north-east of the realm as ''Tetrarch''; and Galilee was assigned to [[Herod Antipas]], who bore the same title. Herod Archelaus' title of ''ethnarch'' designated him as the senior ruler, higher in rank than the tetrarchs and the chief of the Jewish nation; these three sovereignties were in a sense reunited under [[Herod Agrippa]] from A.D. 41 to 44.
Before 63 B.C., Hyrcanus II, grandson of [[John Hyrcanus|Hyrcanus I]], held the title of both ethnarch and [[High Priest]]. (See [[Pompey]].)