Europe is roughly comparable in size and diversity to India or China. Europe has no strikingly obvious eastern boundary – the Ural Mountains are about the same height as the Appalachians, and the Don River was traditionally taken as Europe's eastern boundary instead – and it gradually merges into the steppe. Few thirteenth-century Europeans would even have heard of the word “Europe” (although this would change by the 1600s), and it might be equally appropriate for the purposes of this book to refer to it as Christendom instead.

Pastoral nomads did not establish themselves any farther west than Hungary, the last outpost of the great steppe belt that stretches all the way from Mongolia. Transhumance (the seasonal migration of livestock) was common throughout southern Europe, in the familiar figure of the shepherd and his flocks, but the shepherds were no more nomads than were the cowboys who drove herds of cattle from Texas to Kansas every year – they were marginal members of agricultural societies. Their families, if they had any, lived in villages or towns.

Nevertheless, the horse was enormously symbolic for European culture. In the words of one knight, writing around the year 1250, “No animal is more noble than the horse, since it is by horses that princes, magnates and knights are separated from lesser people, and because a lord cannot fittingly be seen among private citizens except through the mediation of a horse.” Paintings and statues of monarchs on horses were ubiquitous.