This is not an area that I have studied too closely. Obviously there was not an abrupt shift; Arab and Viking raiding continued well past 1000 AD in various places. In the case of the Vikings, I think the record is fairly clear that they eventually got more out of settling in Normandy, Britain, Ireland, etc., and trading from there than they did from the earlier raids, and they adjusted their behavior accordingly. I know less about the Arab side of things, but perhaps someone else in the forums has studied this question.
