The Bulgarians, Slavic in institutions, but not in origin, captured Adrianople in 813 and carried away many Christian prisoners, among whom was the bishop himself, who began the conversion of their captors. In 861 a Bulgarian princess, returning from captivity in Constantinople as a Christian missionary to her own people, converted her brother, the Duke Bogoris. This work was supplemented by Methodius, who was sent there in 862 to help on the good work, and by other Greek missionaries who followed him. In 865 the baptised Duke of Bulgaria wrote to Pope Nicholas I. for Roman missionaries and asked one hundred and six questions about Christian doctrines, morals, and ritual. The Pope sent two bishops and elaborate answers to the questions,[256:1] but the Greek faith finally predominated. The Magyars, who entered Europe in the ninth century and in 884 settled near the mouth of the Danube, finally located in present Hungary. They first learned of Christianity at the Byzantine court. In Hungary, however, they came in touch with the Roman missionaries. Otto the Great compelled them to receive missionaries from the Bishop of Passau. When Prince Geyza married a Christian princess, their conversion was rapid and complete. Adalbert of Prague visited the country and made a great impression. King Stephanus (997) made Christianity the legal religion, enforced the German ecclesiastical system, formed ten bishoprics, located an archbishopric at Grau on the Danube, built churches, schools, and monasteries, and received a golden crown from Pope Sylvester II. in 1000 as "His Apostolic Majesty."[257:1] The Russians claimed St. Andrew for their apostle but probably actually learned of Christianity from Constantinople in the ninth century. Photius, in 867, told the Pope that the Russians were already Christians. A church was built at Kieff on the Dnieper, the Russian capital, and in 955 the grand-duchess, Olga, journeyed to Constantinople and was baptised. Grand-Duke Vladimir, the grandson of Olga, established Christianity at one sweep when he married Anne, the daughter of Emperor Basil and was baptised at his wedding in 988. Churches, schools, and monasteries spread rapidly all over the country, but the Greek Church instead of the Roman was firmly planted there, and in 1325, Moscow became the Russian Rome.[257:2] While the Roman Church was winning new subjects all over northern and central Europe; she was losing nearly as much in territory and numbers in Africa and Spain. This loss was due to the rise of a rival religion in Arabia which bid fair to outstrip Christianity in the race for world conquest.