Not long after the Slavic incursion, Moesia was once again invaded, this time by the Bulgars under Khan Asparukh. Their horde was a remnant of Old Great Bulgaria, an extinct tribal confederacy situated north of the Black Sea in what is now Ukraine and southern Russia. Asparukh attacked Byzantine territories in Moesia and conquered the Slavic tribes there in 680. A peace treaty with the Byzantine Empire was signed in 681, marking the foundation of the First Bulgarian Empire. The minority Bulgars formed a close-knit ruling caste.