The 13 Kohanic Cities are the 13 cities/villages and their respective peripheral territory listed in the Book of Joshua (Joshua 21:13-21) as having been allocated by Elazar and Joshua to the kohanim (Israelite priesthood) and their families. The Kohanic cities are a sub-set of the 48 Levitical cities allocated to sections of the Tribe of Levi.
The Kohanic cities all come along with the detail ואת מגרשה ("the peripheral land around the city") - presumably, this amount is 2000 amah in all directions. These 13 cities are the primary land allotments for kohanim in the Land of Israel and were in use from the initial entry of the children of Israel into the land of Israel up until they were depopulated by Nebuchadnezzar.
According to the Books of Ezra and Nehemiah, these 13 cities where re-inhabited by the kohanim upon their return from the 70-year term of the Babylonian exile.
The areas listed: