During this period of prosperity the kingdom of the Khazars received a considerable Jewish influx from Byzantium, where the Jews were persecuted by Emperor Basil the Macedonian (867-886), being forcibly converted to Christianity, while hundreds of Jewish communities were devastated. The Jewish emigrants from Byzantium were naturally attracted towards a land in which Judaism was the religion of the Government and the Court, though equal toleration was accorded to all other religions. The well-known Arabic writer Masudi refers to this Jewish immigration in the following passage: The population of the Khazar capital consists of Moslems, Christians, Jews, and pagans. The king, his court, and all members of the Khazar tribe profess the Jewish religion, which has been the dominant faith of the country since the time of the Caliph Harun ar-Rashid. Many Jews who settled among the Khazars came from all the cities of the Moslems and the lands of Rum (Byzantium), the reason being that the king of Rum persecuted the Jews of his empire in order to force them to adopt Christianity.... In this way a large number of Jews left the land of Rum in order to depart to the Khazars. This testimony dates from the year 954. Contemporaneous with it is the extremely interesting correspondence between Joseph, the Khagan of the Khazars, and Hasdai Ibn Shaprut, the Jewish statesman of the Cordova Caliphate in Spain. Being a high official at the court of Abderrahman III., Hasdai maintained diplomatic relations with the emperors of Byzantium and other rulers of Asia and Europe, and in this way came to learn of the Khazar kingdom, through the Persian and Byzantine ambassadors. The news of the existence of a land somewhere beyond the seas where a Jew sat on the throne, and Judaism was the religion of the state, filled Hasdai with joy. Firmly convinced that he had found the clue to the lost Jewish kingdom of which popular Jewish tradition had so much to tell, the Jewish statesman at the Moslem court felt the burning need of getting in touch with the rulers of Khazaria, and, in case the rumors should prove correct, of transferring his abode thither and devoting his powers of statesmanship to his fellow-Jews. Prolonged inquiries elicited the information that the land of the Khazars lay fifteen days by sea from Constantinople, that it stood in commercial relations with Byzantium, that the name of its present ruler was Joseph, and that the safest means of communicating with him was by way of Hungary, Bulgaria, and Russia. After several vain attempts to get in touch with the ruler of the Khazars Hasdai finally succeeded in having an elaborate Hebrew epistle delivered into the hands of King Joseph (about 955).