יהושע, פרק י״ג, פסוק כ״ח

Summarizing the inheritance of the tribe of Gad involves gathering together all the various settlements given to its families. A clear distinction is made between two different types of living areas within their granted territory. The first category consists of protected cities that are fortified and completely surrounded by a wall. The second category includes open, unwalled towns and villages that exist without such physical barriers [רש״י].