We have no idea who Hanun was. Zanoah was a town located in the western extremity of Judah’s inheritance (Joshua 15:34), some 20 kilometres distant. Volunteers from that community, presumably under Hanun’s leadership, made the trek to (distant) Jerusalem to assist in its reconstruction. Obviously, they needed accommodation in the city for the duration of their labours.
13 Hanun and the inhabitants of Zanoah repaired the Valley Gate. They rebuilt it and set its doors, its bolts, and its bars, and repaired a thousand cubits of the wall, as far as the Dung Gate.