Early 1900s: There are some eleven million speakers of the Yiddish language.

Late Twentieth Century: Approximately half of the world's population of Yiddish speakers have been killed in the Holocaust.

Early 1900s: Poland is part of the Russian empire under the Tsar (Czar).

Late Twentieth Century: With the breakup of the Soviet Union, formerly under communist rule, Poland becomes an independent nation.

Early 1900s: The shtetls in Warsaw, Poland, include a high concentration of the Jewish population, and are a locus of Jewish culture.

Late Twentieth Century: Much of the population of Polish Jews has perished in the Holocaust, while others have left Poland to escape such persecution.

Early 1900s: The aborted Russian Revolution of 1905 leaves the empire still under the rule of the Czar. However, the Russian Revolution of 1917 leads to decades of communist rule.

Late Twentieth Century: The USSR suffers from internal...