c.1300, "tract of land of a considerable but indefinite extent," from Anglo-French regioun, Old French region "land, region, province" (12c.), from Latin regionem (nominative regio) "a district, portion of a country, territory, district; a direction, line; boundary line, limit," noun of state from past participle stem of regere "to direct, rule" (see regal). Phrase in the region of "about" (of numbers, etc.) is recorded from 1961.