This week marks the death anniversary of King Boleslaw V (The Chaste) in 1279. Boleslaw followed the tradition of his predecessors in Poland by creating incentives for Jewish settlement in Poland, including the establishment of Magdeburg Recht. Ultimately, these policies proved extremely attractive to Ashkenazi Jews from the Rhineland, making Poland a great center of Jewish civilization by the early modern period.
I found it astonishing how money really was the factor that ruled the Jews during this time period. Yes, their was plenty money opportunity in Poland, but your life complete is going to change and your leaving behind everything you built.