I still haven't remembered to hunt down any of Cavalli-Sforza's surveys of archaeogenealogy (or whatever the right term is-- human population cladistics?), but surely the trans-Mediterranean interchange before the Punic Wars (http://en.wikipedia.org/wiki/North_Africa_during_the_Classical_Period) would've predated the major period of Arabic/Moorish influence (http://en.wikipedia.org/wiki/Maghreb)? Mind you, geography all gloops into one big blur for me, so mumbly handwaving.