Emperor Basil II Porphyrogenitus sought to restore former territories of the Byzantine Empire. By 1000, Basil II had fought off his own nobility and defeated the Islamic threat from the east, and so led another invasion of Bulgaria. Bulgaria had been partly subjugated by John I Tzimiskes after the invasion of Svyatoslav I of Kiev but parts of the country had remained outside Byzantine control under the leadership of Samuel and his brothers.