The geonim (Heb. geʾonim; sing. gaʾon) were the heads of the yeshivot (academies of higher learning) in Iraq, Palestine, Syria, and Egypt between the sixth and thirteenth centuries. The office of gaon combined religious, legal, and political functions. Its incumbents had followers all over the Islamic world and in Christian Europe, and their works laid the foundation for all subsequent developments in Jewish law.  The title gaon is an abbreviation of rosh ye…