In Rabbinic historiography it is common to name periods after the authorities of the time. Ga'on (plural: Ge'onim) was the title of the head of the Yeshiva (religious academy). The title Ga'on originated in the Babylonian yeshivot of Sura and Pumpidita, although this title was adopted also by the heads of the Yeshiva of Eretz Israel. During the Geonic period, the Babylonian yeshivot held an important position in Jewish life and influenced the Jewish communities throughout the Diaspora. Numerous students from all over the world came to study in Babylonia, and later returned to their hometowns to serve as religious leaders. The contacts between the Babylonian yeshivot and the diaspora were maintained through the responsa literature and by agents who traveled abroad and functioned as preachers, justices and teachers.