Klezmer music has its origins in Yiddish-speaking eastern European Jewish communities. They mainly lived in the countries that are now Romania, Ukraine, Belarus and Poland, but were then part of the Russian or Ottoman Empires. The area most klezmorin lived in was known as the Pale of Settlement, and stretched from the Baltic to the Black Sea.
Map of the Pale of Settlement, 1795-1917
Image courtesy of Prof. Eliach & The Shtetl Living History Museum