The absorption of the Christianised Slavs by the Greeks was occasionally interrupted by the Bulgarian inroads, which now became frequent. Since the foundation of the first Bulgarian Empire towards the end of the ninth century, the power of that race had greatly increased, and the Byzantine sovereigns found formidable rivals in the Bulgarian tsars. About 929 the Bulgarians captured Nikopolis, and converted it into a Slavonic colony, which was only reconquered by considerable efforts. Arsenios, Metropolitan of Corfù, who was canonised later on, and was for centuries the patron saint of the island, where his festival is still celebrated and his remains repose, fell into the hands of these invaders, but was rescued by the valour of the islanders[40], and a new tribe, called Slavesians, probably an offshoot of the Bulgarians, made its way into the Peloponnese. The troublesome clans of Melings and Ezerits seized this opportunity to demand the reduction of their tribute, which had been raised after their last rising. The Government wisely granted their demand, and so prevented a formidable insurrection. Athens was also disturbed by a domestic riot. A certain Chases, a high Byzantine official, had aroused the resentment of the people by his tyranny and the scandals of his life. Alarmed at the threatening attitude of the inhabitants, who had been joined by others from the country, he took refuge at the altar in the Church of the Virgin on the Akropolis, the ancient Parthenon. But the sanctuary did not protect him from the vengeance of his enemies, who stoned him to death at the altar, thus showing less reverence for the Virgin than the ancient Athenians had once shown under somewhat similar circumstances for the goddess Athena.