ABSTRACT
Chisdai Abu-Yusuf, the son of Isaac the son of Ezra, of the family of Shaprut, a physician, became Vizier to the Caliph Abd er-Rahman III (911-61) and his successor the Caliph Hakem (961-76). The Byzantine Emperor, Romanus II, driven into straits by the Abbaside Caliph at Bagdad courted the friendship of Abd er-Rahman and sent him a Greek medical manuscript of Dioscorides, in charge of a Monk, Nicolaus, to interpret the Greek into Latin. Nicolaus became Chisdai's friend. Chisdai was sent by Abd er-Rahman to Navarre and cured its deposed King Leon of obesity and helped to restore him to his throne of Navarre. Otto I, Emperor of Germany in 956, sent an embassy to the Caliph Abd er-Rahman, and Chisdai carried on the negotiations which led to a satisfactory treaty. As Nasi (Prince) or temporal head of the Jewish congregations of Cordova, Chisdai advanced Jewish interests and Jewish studies in Spain and elsewhere. He had heard from Oriental travellers that there was a Jewish kingdom in Asia ruled by a Jewish King. Once he was told by merchants from Choresvan (Khorasan) that such a Jewish kingdom did really exist and that the land was called Khozar. He had also heard of Eldad the Danite. Ambassadors from the Byzantine Emperor to the Caliph had told Chisdai that the merchant's story was true, Chisdai accordingly sent one Isaac ben Nathan with a letter, of which a translation follows, with a recommendation to the Emperor. Isaac remained six months in Constantinople, but went no further, the Emperor writing that the way to the land of Khozar was far too dangerous and the Black Sea only occasionally navigable. Chisdai thought of sending his letter to Jerusalem, where Jews had promised to forward it to Nisibis, thence to Armenia, from Armenia to Berdaa, and from thence to Khozar. But while he was considering this plan, Ambassadors came from the King of the Gebalim (Slavonians) to Abd er-Rahman, among whom were two Jews, Saul and Joseph. These offered to hand the letter to the King of Gebalim, who out of respect for Chisdai would send it to the Jews in Hungary, thence it would be forwarded to Roumelia and Bulgaria and so finally reach its destination. By these means the letter was delivered to Joseph the King of the Khozars, and the King sent him a reply of which a translation is also given. Chisdai is believed to have died in 1014. The authenticity of these letters, now generally accepted, was for a long time impugned by Buxtorf, Basnage and others. The great poet philosopher, Judah Halevi, in 1140 wrote the famous work Cusari which is based on the conversion of the King of the Khozars, who inhabited the Crimea, and of a portion of his people. This took place according to the Arabian historians in the second half of the eighth century.
