Probably dark skin - you'd have to get an annotated edition of Child Harold to find out what a Suliote is. My WAG would be an Assyrian (partly because of the wolves/flocks idea). But dark skin in literary contexts often implies an enigmatic or withdrawn character - Othello, Heathcliff...
Incidentally, the "'larum" is related to alarm - a call to arms (probably on a brass instrument).
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