Klezmer = Jewish Musician

Klezmer originally referred not to a musical style but to the musicians who played at the celebrations after
weddings, bar mitzvahs and holidays like Hanukkah.

With Jewish communities scattered across Eastern and Central Europe, klezmer repertoire came to include a huge range of material, often drawn from the folk music of neighboring peoples, particularly Gypsies, or Rom.

The music evolved and thrived in the early 20th century as Jews poured into the United States and encountered jazz, blues and Broadway, though by the 1960s klezmer was largely seen as sentimental ethnic kitsch

http://www.davidkrakauer.com/epk/krakauer_sfchronicle.pdf