Who were the Ge'onim?

One of the most important periods in Jewish history was the period of the geonim (600-1000 C.E.). During this period, Jewish life was centered in Babylon where there were two great Yeshivot (schools). The heads of these schools were called Ge'onim, The Ge'onim were effectively the leaders of world Jewry during this period. A fascinating discussion about the Ge'onim and  the Ge'onic period.