Playing my first VI campaign as the Northumbrians (also first campaign on MTW overall) and I'm wondering how you win 100% of the provinces if, apparently, non-Viking factions can't make the ships that can cross the North Sea. (I'm not at the point yet where those are the only provinces left to take - I'm just wondering about this.) Looking at the VI tech tree, Vikings can built one level of ship higher than everyone else's longboats. The regular longboats (and smaller boats) available to the non-Vikings can't go into the North Sea (can't leave coastal waters). So I'm wondering how you eventually take Norway and Jutland to get the full 100% if you don't have access to the Viking super-longboats.

Thanks