When horses arrived on the Great Plains of North America, they transformed everything. The plains previously were difficult places in which to live – they were abundant in bison, but hunting the great herds meant trapping them in places where they could be chased off of cliffs or ambushed. But a hunter on horseback could pursue bison herds at their own pace, for miles. Over a century, a whole way of life emerged around the horse and the mounted warrior, leading to the legacies of the great indigenous tribes of the plains: the Lakota (and other "Sioux" groups), the Apsáalooke (Crow), the Tsitsistas (Cheyenne), and others.

Similarly, but over a longer period of time, on the steppes of Asia, horse-bound nomadic pastoralists developed new technologies – most significantly the composite bow, which can be fired with the strength of a longbow, but is smaller and suitable for cavalry – that allowed them to stage devastating raids into settled lands. In addition to the Mongolians and Scythians, groups such as the Xiongnu, the Saka, the Kazakhs, and various Turkic-speaking peoples created vast, highly mobile armies that posed an existential threat to (complacent) cities. Nearly every agricultural state bordering the steppe has legends of conflicts (and defeats from) these groups: the Great Wall was built to counter Xiongnu raids, Korean history talks about struggles with the Jurchen, and the Romans had their Hunnic threat. All this came from the deep bond between horse and human, a link that we today have largely lost, as we turn towards combustion engines, treads and tires.