The zeal with which the Karaites sought to exalt their creed over Rabbanism had the desired effect of spreading it widely about the middle of the tenth century. They penetrated to Spain, and attained influence in Africa and Asia. We know that the Egyptian Rabbanites accepted much from the Karaites. Moses and Aaron ben Asher, a father and son of Tiberias, exercised a powerful influence at this period (890-950). They were grammarians and Massorets. They wrote on the Hebrew accents and Biblical orthography, but in so clumsy a style and such miserable verse, that their observations are for the most part incomprehensible. But these insignificant works were of no importance, while considerable value attached to the copies of the Bible, which were corrected by them with the greatest care and exactness according to the Massoretic rules, which they had mastered completely. The Ben-Asher copies of the Bible were looked upon as models both by the Karaites and the Rabbanites, and treated as sacred. New copies were afterwards made from these in Jerusalem and Egypt. The Massoretic texts of the Bible now in use are largely derived from Ben-Asher's original copies, because the Rabbanites afterwards overlooked the fact that the scribe was a Karaite. Saadiah, on the contrary, who had known Ben-Asher, the son, was dissatisfied with these Massoretic works, and wrote a very keen polemic against him. In addition to Saadiah, Ben-Naphtali raised objections against the results of Ben-Asher's Massoretic investigations, though mostly on insignificant points. Nevertheless, the text of the Bible according to the Massorets of Tiberias maintained its superiority. The old Eastern signs for vowels and accents to the Bible text were changed, extended and improved, by the Massoretic school of Ben-Asher.