Idumea lay south of Jerusalem, in the region historically associated with Edom. During Hasmonean expansion, Idumean populations were incorporated into the Jerusalem-centered polity and took on Yahweh allegiance and ancestral law. Ancient sources present this as a politically driven incorporation, though the lived process likely varied by town, family, and elite interest.

The historical importance is large because Herod the Great came from an Idumean family. Idumean incorporation therefore became central to late Second Temple politics, kingship, Rome-facing diplomacy, and the Herodian dynasty. The stream is Abrahamic color because it represents cultural incorporation into Yahweh allegiance, not a separate institutional sect.