For almost three millennia the pastoral nomads of the Eurasian steppe formed a great reserve of mounted cavalry, threatening their settled neighbours while offering them goods and services of great value – in particular horses and skilled soldiers for their armies. The Eurasian nomads were also empire-builders, creators of imperial ideology and administrative structures that were passed down through generations of successor states. Their imperial centre in Mongolia was home to two related peoples – the Turks and the Mongols – each defined by the powerful empires they erected. The Türk Empire, which flourished from the mid-sixth to mid-eighth centuries, was the first of these and it controlled the steppe from Mongolia to the Volga river, fighting and trading with China, the empires of the Middle East, and Byzantium. The second great state was the Mongol Empire, founded by Chinggis Khan in 1206. The Mongols extended their power yet further than the Turks, conquering much of Eurasia.