In a similar fashion, the Date clan was called the "Idate" clan at the beginning; the name, "IDATE no Kamonnosuke Tamekage" appears in the article of 1339 written during the Muromachi Period, and Masamune DATE introduced himself as "Masamune IDATE" in a letter presented by Tsunenaga HASEKURA to Pope of the Catholic Church in 1613.
伊達氏も本来は「いだて」であり、室町時代の延元4年（1339年）の文書に「いたてのかもんのすけ為景」、慶長18年（1613年）に支倉常長がローマ教皇に渡した伊達政宗の書簡にIdateMasamuneとある。