Talmudic thought in medieval Ashkenaz effectively begins with
Gershom ben Judah, or Rabbenu Gershom as he is usually
called. He headed the academy at Mainz and composed a
talmudic commentary (embellished by his successors at Mainz)
as well as liturgical poems and many responsa. Rabbenu
Gershom is perhaps best known, however, for the series of
ordinances attributed to him, which deal with a wide variety
of issues including polygamy, personal privacy, and communal
government. (from Introduction)
Kanarfogel, E. (2000). Gershom ben Judah. In Michael Terry (ed.), "Reader's Guide to Judaism" (pp. 209-210). Chiacgo: Pitzroy Dearborn.
*This is constructed from limited available data and may be imprecise.