The advent of the First Crusade (1099)1 conveniently marks the exhaustion of the stream of Karaite literary effort which had flowed forth for a considerable period. The flourishing age of the tenth and eleventh centuries had witnessed a brilliant succession of grammarians, lexicographers, exegetes, legal authorities and apologists,2 who had graced the Karaite camp in the drawn battle with Rabbinism. Especially influential in this verbal warfare was the school at Jerusalem associated with the name of Abu Ya'qub Joseph ben Nuh3 and carried on by his students, Abu'l-Faraj Harun, the famous "grammarian of Jerusalem", and Abu Ya'qub al-Basir, the philosophical genius of the Karaites. The pupil of al-Basir, Abu'l-Faraj Furqan Ibn Assd (Jeshua ben Judah), succeeded his teacher as the attraction of this intellectual center and influenced Jewish thought as far away as Spain.4