Hasdai ibn Shaprut continues to perform important services for Caliph al-Hakam II, in whose reign he will die.

Hasdai fosters the study of Jewish law and the Talmud (the rabbinic compendium of law, lore, and commentary), thereby making Spanish Jewry relatively independent of the Eastern Talmudic academies.

Hasdai's correspondence with a Jewish Khazar king, Joseph, written by Menahem ben Saruq, is of historic importance.

Allegedly, When he heard that in Central Asia there was a Jewish state with a Jewish ruler, he desired to enter into correspondence with this monarch; and when the report of the existence of the state of the Khazars was confirmed by two Jews, Mar Saul and Mar Joseph, who had come in the retinue of an embassy from the Croatian king to Córdoba, Hasdai entrusted to them a letter, written in good Hebrew addressed to the Jewish king, Joseph ben Aaron, in which he gave an account of his position in the Western state, described the geographical situation of Andalusia and its relation to foreign countries, and asked for detailed information in regard to the Khazars, their origin, their political and military organization, etc.

A man of extensive contacts and virtually unlimited resources, Hasdai had learned of the existence of the Khazars from Khorasani merchants.

His ignorance of the Khazar state is odd, and may even have been disingenuous, given Joseph's statements to the effect that there had been communications between the two communities in the past.