When did horses become common on the Great Plains?

The arrival of the horse on the Great Plains was a gradual process that occurred over the course of at least a century. While horses were relatively rare in the region before 1650 CE, they became common by 1750 CE.1

Indigenous peoples of the Great Plains acquired these animals primarily from Spanish New Mexico in the late 17th century, as well as through the expansion of feral herds. The integration of the horse into Plains life was transformative, significantly increasing human mobility and productivity. This shift allowed many groups to adopt a nomadic lifestyle centered on hunting bison, leading scholars to divide the history of the region into distinct pre-horse and post-horse periods.2314