were sent from Babylonia and the neighboring lands. Jewish communities in these regions had religious leaders who were somewhat acquainted with the Talmud, and who could on occasion visit the Jewish academies in Babylon. A literature of questions and answers developed, known as the responsa literature. The questions were usually limited to one or more specific cases, while the responsum to such a query gave a ruling, a concise reason for it, together with supporting citations from the Talmud, and often a refutation of any possible objection. More discursive were the responsa of the later geonim after the first half of the 9th century, when questions began to be sent from more distant regions, where the inhabitants were less familiar with the Talmud, and were less able to visit the Babylonian academies, then the only seats of Talmudic learning. The later geonim did not restrict themselves to the Mishnah and Talmud, but used the decisions and responsa of their predecessors, whose sayings and traditions were generally regarded as authoritative. These responsa of the later geonim were often essays on Talmudic themes, and since a single letter often answered many questions, it frequently became book-length in size. Two important examples of such books are the Siddur of Amram Gaon, addressed to the Jews of Spain in response to a question about the laws of prayer, and the Epistle of Sherira Gaon, which sets out the history of the Mishnah and the Talmud in response to a question from Tunisia. Some of the responsa that have survived are in their original form, while others are extant only as quotations in later works. Many have been found in the Cairo Genizah. Examples of responsa collections are:Halakhot Pesukot min ha-Geonim (Brief Rulings of the Geonim): Constantinople 1516Sheelot u-Teshuvot me-ha-Geonim (Questions and Answers/Responses from the Geonim): Constantinople 1575Shaare Tzedek (Gates of Justice), edited by Nissim ben Hayyim: Salonica 1792, containing 533 responsa arranged according to subject and an index by the editorTeshuvot Ha-Geonim, ed. Mussafia: Lyck 1864Teshuvot ha-Geonim: Shaare Teshuvah with commentary Iyye ha-Yam by Israel Moses Hazan: Livorno 1869; linked hereShaare Teshuvah ha-Shalem, ed. Leiter: New York 1946Teshuvot Geone Mizrach u-Ma'arav, ed. Mueller: Berlin 1888 Lewin, B. M., Otzar ha-Geonim: Thesaurus of the Gaonic Responsa and Commentaries Following the Order of the Talmudic Tractates (13 vols): Haifa 1928 Assaf, Simhah, Teshuvot ha-Geonim: Jerusalem 1927 (second volume 1942). Other works Individual Geonim often composed treatises