>>507204611
East Asian men were in Europe as early as 4th Century (Avars) and continued that way all the way to the 15th Century with Golden Horde / Genghis Kahn. Teh literal reason why Hitler didnt consider Slavs as 'white' is due to the race-mixing / conquering that happend for millennia between Asian men and White females as they conquered into Europe.

https://www.science.org/content/article/mystery-warriors-made-fastest-migration-ancient-history