It seems that your whole proposition is based upon the notion that the hordes were unstoppable, and only retreated out of self interest. This contradicts the fa

It seems that your whole proposition is based upon the notion that the hordes were unstoppable, and only retreated out of self interest. This contradicts the fact that mongols were defeated in East and Central Europe, and retreated right after. It also dismisses the historical trading routes in the Mediterranean sea, and direct access to Northern Africa and the Atlantic ocean. Still, European powers were at a constant war of conquests with Islamic kingdoms from Northern Africa and Middle East. Bottom line, your idea contradicts centuries of war in Europe.