Yefet ben Ali lived during the 10th century, a native of Basra in the area of present-day Iraq. He is perhaps the foremost Karaite commenter of the "Golden Age of Karaism". His commentaries, which were written in Arabic, covered the entire Tanakh. They were accompanied by a very literal translation of the Hebrew text, which often violated the rules of Arabic grammar. These writings influenced the rabbinical sage Ibn Ezra, who quotes Yefet fourty-two times in his commentary of the minor prophets. There is a legend among some Karaites which states that Ibn Ezra was a student of Yefet ben Ali.

His commentaries borrowed much from his predecessors, and in fact he occassionally borrows from Rabbinical sources, such as the Targums, the Talmud, and the works of Saadia Gaon. He was also known for his expertise of Hebrew grammar, and for his polemics against Rabbinic Judaism, Islam, and Christianity. Later in his life, he immigrated to Jerusalem, where he died.