Where the Allen name comes from

Allen turns up across England, Scotland, Wales and Ireland, which is a clue to how many roads it travelled to get here. The Gaelic Ailin behind it carries two meanings at once, little rock and harmony, and there is a separate Celtic word, Aluinn, meaning handsome. In Ireland the name is the anglicised form of O h-Ailin. Allan, Alan and MacAllen are the same name written by different hands.