Pentanglia = England, Wales, Scotland, Northern Ireland, and the Republic of Ireland
Pentanglia is a convenient name for the part of the world that is composed of these five nations: England, Wales, Scotland, Northern Ireland, and the Republic of Ireland. Pentanglia is a convenient way of avoiding terms like "the British Isles" which imply that all of the islands are British. Better to say, for example, the Pentanglian Isles or the Islands of Pentaglia.