For roughly five centuries the largest Jewish population in the world lived in this region, mostly in the Polish-Lithuanian Commonwealth and its successor territories, and the institutions it built there are the direct ancestors of most Jewish religious life today.
Hasidism began in its southeastern corner in the eighteenth century, in Podolia and Volhynia. Israel ben Eliezer, known as the Baal Shem Tov, gathered a circle around a piety centred on joy, on prayer as attachment to God, and on the figure of the righteous man as a channel between his followers and heaven. Moshe Rosman's study of the sources shows how much of the familiar biography comes from tales collected long afterwards and how little from documents of the man's own lifetime, which is a caution rather than a debunking. The movement organised itself into courts around particular dynasties, spread rapidly, and was fiercely opposed by the rabbinic establishment of Lithuania before eventually being accepted as part of the tradition.
Almost all of it was destroyed between 1939 and 1945. The communities of Poland, Hungary, Slovakia and the Czech lands were murdered in place or deported to killing centres built in the same region, and the yeshivas and Hasidic courts that survived did so because individuals reached Israel, the United States or Britain and rebuilt them there. The map of Jewish religious life was redrawn by that, permanently.