From my Irish name book ...numerous especially in the Belfast area and Tyrone and in Ulster generally. Some found in Cork. They were originally a Scottish family who settled in Longford in 1620. The name in Ulster is generally Scottish. It is also an anglicisation of Mac Firbhisigh (man of prosperity), a family of poets and historians attached to the Ui Fiachrach (in Mayo-Sligo). They complied the Book of Lecan in 1417.