hajnal line. it lowered interbreeding, excluded losers from gene pool, allowed nuclear families to migrate to places with better economic value. it did work for spain too but spain got resource curse because they got free gold while not having strong enough institutions. before that their king was restricted by spanish parliament like in england.       other way around. first it became rich, capitalism started to form there and only then people moved there.   why not southern spain or sicily or constantinople? they were major trade centers before. it's just insititutional and technologic progress happened inside the banana which created supply (of industrial goods) and demand (of colonial goods). you can't trade if people are dirt poor.
Belarus