I was doing a Arabia game, and I noticed in 1200 that the tech leader was the Vikings. I checked again in 1300 and it was still the Vikings. I opened the WB at this point and checked that they vastly outpaced the other European civs (except Byz). I already mentioned a few days ago in this thread that Vikings are very fast in tech. To confirm it I rolled 5 Ottoman Starts in the 600AD Scenario with Monarch Difficulty and Normal Speed. The result was: In 3 cases the Vikings were the #1 tech leader with no equals. In 1 case they were in seconded only by the Arabs, who survived the Turkic invasion, by a single tech. In 1 case they were on 2nd place along with Germany. 1st place were France and Italy. Again, they were seconded by a single tech. I observed in other games that the Vikings are very fast in tech not only in the Medieval Era, but through all eras. But this is hard to show in test cases because 1) later starts mean longer loading time and 2) Vikings are highly unstable after Renaissance and keep collapsing/respawning. Considering that the Scandinavian region does not have a lot of commerce (few river tiles, no commerce resource except one silver and fur) and that the Vikings always have Conquest civic, I must conclude that their tech modifier must be way too good. TL DR; Viking tech speed is overpowered.