Charles Ellicott Commentary Ezra 4:1

"Now when the adversaries of Judah and Benjamin heard that the children of the captivity were building a temple unto Jehovah, the God of Israel;" — Ezra 4:1 (ASV)

The adversaries. —The Samaritans, so termed by Nehemiah (Ezra 4:11). These were a mixed race, the original Israelite element of which was nearly lost in the tribes imported into the northern part of the land by Sargon, Sennacherib, and Esar-haddon. (See 2 Kings 17:24–34.)