JUDAH BEN MEÏR HA-KOHEN HAZAḲEN:

Yehuda ben Meir, also known as Yehuda ha-Kohen or Judah of Mainz, was a German rabbi, Talmudic scholar and traveler of the late tenth and early eleventh century CE. His book Sefer ha-Dinim contains an account of his travels and those of other Jews in Eastern Europe. In this work, Przemyśl and Kiev are mentioned as trading sites along the Radhanite trade network. Yehuda was the principal teacher of Gershom ben Judah, and his work was highly influential on the later writings of Rashi.

• Yehuda was surnamed, according to some sources, either "Léon", "Léonṭe", "Léonṭin", "Sire Léon", and "Sire Léonṭin", and was designated as "the grand" and "the gaon."