Kerns and Gallowglasses are in Scotland and Ireland. Welsh longbowmen and speamen too. In the low countries you can get Flemish pikemen, Swiss pikemen in Switzerland. Bulgarian brigands are all over the balkans, slav spearmen and archers as well. Alan cavalry, Cuman horse, Turkomans, Armenian cavalry, and archers in Asia minor. You can recruit some crusader units without a crusade around Rome. These are the none generic mercs I've come across.