1. Harold Peake and Herbert John Fleure, The Steppe and the Sown, New Haven: Yale University Press, 1928.
2. See the studies by Thomas Barfield, The Perilous Frontier, Oxford: Blackwell, 1989,
3. and Anatoly Khazanov, Nomads and the Outside World, Cambridge: Cambridge University Press, 1984.
4. For a revisionist view see Christopher Beckwith, Empires of the Silk Road: A History of Central Eurasia from the Bronze Age to the Present, Princeton: Princeton University Press, 2009.
5. René Grousset, Empire of the Steppes, tr. Naomi Walford, New Brunswick, NJ: Rutgers University Press, 1970, p. ix.