Like most other main characters, Demandred is likely based on several people (maybe also Hannibal). However, that doesn't mean that he has to do something, that would resemble Hannibal crossing the Alps with elephants.

We never see Demandred wearing Sharan clothes. The comments of other Forsaken indicate that Demandred is somewhere in the Westlands.

I believe Demandred cleverly avoided the big countries like Andor, Tear and Illian, which quickly got Rand's attention and led to the deaths of the Forsaken there. He just caused much chaos with the Dragonsworn at the beginning and later took over a promising country like Murandy to fulfill his military ideas.