In answer to this appeal the emperor sent the two brothers Cyril and Methodius, who were Greeks of Salonika and had considerable knowledge of Slavonic languages. They composed the Slavonic alphabet which is to-day used throughout Russia, Bulgaria, Serbia, and Montenegro, and in many parts of Austria-Hungary and translated the gospels into Slavonic; it is for this reason that they are regarded with such veneration by all members of the Eastern Church. Their mission proved the greatest success (it must be remembered that at this time the various Slavonic tongues were probably less dissimilar than they are now), and the two brothers were warmly welcomed in Rome by Pope Adrian II, who formally consented to the use, for the benefit of the Slavs, of the Slavonic liturgy (a remarkable concession, confirmed by Pope John VIII). This triumph, however, was short-lived; St. Cyril died in 869 and St. Methodius in 885; subsequent Popes, notably Stephen V, were not so benevolent to the Slavonic cause; the machinations of the German hierarchy (which included, even in those days, the falsification of documents) were irresistible, and finally the invasion of the Magyars, in 893, destroyed what was left of the Slavonic Church in Moravia. The missionary brothers had probably passed through Bulgaria on their way north in 863, but without halting. Many of their disciples, driven from the Moravian kingdom by the Germans, came south and took refuge in Bulgaria in 886, and there carried on in more favourable circumstances the teachings of their masters. Prince Boris had found it easier to adopt Christianity himself than to induce all his subjects to do the same. Even when he had enforced his will on them at the price of numerous executions of recalcitrant nobles, he found himself only at the beginning of his difficulties. The Greeks had been glad enough to welcome Bulgaria into the fold, but they had no wish to set up an independent Church and hierarchy to rival their own. Boris, on the other hand, though no doubt full of genuine spiritual ardour, was above all impressed with the authority and prestige which the basileus derived from the Church of Constantinople; he also admired the pomp of ecclesiastical ceremony, and wished to have a patriarch of his own to crown him and a hierarchy of his own to serve him. Finding the Greeks unresponsive, he turned to Rome, and Pope Nicholas I sent him two bishops to superintend the ecclesiastical affairs of Bulgaria till the investiture of Boris at the hands of the Holy See could be arranged. These bishops set to work with a will, substituted the Latin for the Greek rite, and brought Bulgaria completely under Roman influence. But when it was discovered that Boris was aiming at the erection of an independent Church their enthusiasm abated and they were recalled to Rome in 867.