Jack,
This type kaskara with the Thuluth etching on the blade and the cast copper alloy crossguard is a fairly common thread on the Forum. Jim is the resident expert on the subject. Search on Thuluth Kaskara for excellent discussions. The first thread plus one from 2010 have much information if little conclusions re Sudan.
http://www.vikingsword.com/vb/showthread.php?t=26896
http://www.vikingsword.com/vb/showthread.php?t=12225
Sometimes I think these swords were made in Omdurman at the close of the Mahdiya and at others made in Egypt and exported to Sudan again toward the end. No real objective reason to believe that either is correct.
Regards,
Ed