The WHB Act protected horses and burros on lands where they were found when the law was signed by President Nixon in December 1971. Some of those lands are managed by the Bureau of Land Management (BLM), some are managed by the U. S. Forest Service (USFS). Lands managed by the USFS are called ‘Territories.’ BLM uses the term ‘Areas.’
The USFS FAQ page provides a history of equines in North America, stating that horses and burros are indigenous species, evolving on the continent with its grasslands.
This contradicts one of the elements in the wild horse narrative, namely, that horses are non-native animals.
Ten to twelve thousand years ago, most of the large mammals became extinct in North America, including horses, mammoths and saber-tooth tigers. Horses returned to the continent with the arrival of Spanish explorers.
Ian Tyson’s La Primera, the soundtrack in this video, takes it from there. The story is told from the horse’s viewpoint. H/T Sandy Palen at Wild in the Pryors.