The improvement in the condition of the Jews of Spain, which began with the Arabic conquest of that country in 711, made itself felt in their literary activity. Especially was this the case in the Caliphate of Cordova, under Abderrahman (912-961). At his court, Hasdai ibn Shaprut rose to prominence, and, like the Mohammedan nobles of the time, gathered around him a number of eminent authors and scholars. Among them were Menahem ben Saruk and Dunash ibn Labrat, who first laid the foundation for a scientific Hebrew grammar. Their disciples were Judah Hayug and Mervan ibn Ganah, called Marinus. The center of Jewish learning still remained in Babylonia, where, after the conquest of the Persians by the Mohammedans, a revival of learning took place. The two principal schools were those of Sura and Pumbeditha, and at the head of each was a president, ‏‎ריש מתיבתא‎‏. The one at Sura was the higher in rank, and was called Gaon (excellency), a title which later was transferred to the president of the school in Pumbeditha. The function of the Gaon was to preside over the regular course of studies, Sidra, and the popular extension course called Kalla, held twice a year in the months preceding the Passover and the fall festivals. He further rendered decisions in important cases submitted to him from all parts of the world. A number of collections of these decisions called Teshubot (Responsa), have come down to us. They are written partly in Aramaic and partly in Arabic, according to the language in which the question was written. The Gaon licensed rabbis, or judges, as they were called, because their chief function was to act as judges in civil cases. These licenses were endorsed by the Exilarch, Resh Galutha, the political head of the communities in Babylonia, representing them before the government and appointing the Gaon. The former, in turn, was appointed by the Caliph, and his office was hereditary as a rule. The oldest literary works of the period are collections of laws regarding matters of frequent occurrence, such as liturgy, mourning, the reception of proselytes, etc. They are known as the “Small Tractates,” and are usually found in the ninth volume of our editions of the Talmud. Other compendia of the law are the Halakot Gedolot by Simeon Kayara, written in the eighth century, and the Sheeltot of Ahai of Shabha, the latter arranged according to the Pentateuch, and containing some moral lessons besides the legal exposition of the text. The compilation of these works was opposed by the Gaonim, who considered them injurious to the study of the law and detrimental to their own authority.