Hello.

This town is signed on an old Soviet map as ‘Саадун’ (Saadun). Proof: http://loadmap.net/download/438996375/200k–c35-08.gif There is a little difference in coordinates (11.27/25.13 in OSM; 11.16/25.08), but remember: - there was no GPS at Soviet period, so little mistakes are possible; - Saadun looks like your unknown town: angle of street grid, empty NWW part of town, little river on the north side.

Well, there is a town Sa’dun on another map: http://www.lib.utexas.edu/maps/ams/africa/txu-oclc-6589746-sheet19-4th-ed.jpg

Probably, “Sa’dun” is an old name of ‘Gereida’, such as ‘Leningrad’ and ‘Saint Petersburg’ in Russia?

Please excuse me if I’m wrong.