Rehoboam lived in Jerusalem, and built cities for defense in Judah.
TSK
TSK · 2 Chronicles 17:2
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Abijah pursued after Jeroboam, and took cities from him, Bethel with its towns, and Jeshanah with its towns, and Ephron with its towns.
These were those who waited on the king, besides those whom the king put in the fortified cities throughout all Judah.