The mustang is a feral horse native to the Western United States. These animals are descended from horses originally brought to the Americas by Spanish conquistadors. While they are commonly referred to as wild horses, they are technically classified as feral because they originate from once-domesticated livestock.
Modern mustangs exhibit varying phenotypes due to contributions from many different breeds and types of horses over time. However, some free-roaming populations remain relatively unchanged from the original Spanish stock, particularly those located in the most isolated areas.