 The name is derived from the elements "gall" ("stranger") + "Breathnach" ("Briton"), meaning "British foreigner".The elements used in the surname would denote the differences between the Gaels—who have been generally thought to have begun migration to Scotland in about the 5th century—and the native Welsh speaking Britons, particularly those of the Kingdom of Strathclyde.The Strathclyde Britons remained a distinct ethnic group from both the Highland Gaels and Lowland Angles until the 14th century.