The thirteenth tribe

"The Khazars (Turkish: Hazarlar) were a semi-nomadic Turkic people who created one of the largest states of medieval Eurasia, Khazaria, with its capital at Atil. Astride one of the major arteries of commerce between northern Europe and southwestern Asia, Khazaria commanded the western marches of the Silk Road and played a key commercial role as a crossroad between China, the Middle East, and Europe."--Wikipedia.