Note 61 — Chapter VIII · THE SPREAD OF ISLAM AMONG THE MONGOLS AND TATARS.
Reading edition
Another race many years before had tried to win the Russians to Islam but had likewise failed, viz. the Muslim Bulgarians who were found in the tenth century on the banks of the Volga, and who probably owed their conversion to the Muslim merchants, trading in furs and other commodities of the North; their conversion must have taken place some time before A.D. 921, when the caliph al-Muqtadir sent an envoy to confirm them in the faith and instruct them in the tenets and ordinances of Islam.61