Wild horses are a type of free-roaming horse found in many parts of the world. The term 'wild horse' can refer to four different species: MUSTANG, BRONC, BRONCO, Brumby, and Tarpan. MUSTANG is a free-roaming horse of the American West that first descended from horses brought to the Americas by the Spanish. BRONC is a term used in the United States for an untamed horse, especially one used in rodeos. BRONCO is a Spanish word meaning 'ROUGH' or 'UNBROKEN, ' and is used to describe a wild or half-tamed horse of the western United States. Brumby is an Australian term for a free-roaming horse of the outback. Tarpan is an extinct wild horse of Eurasia that lived during the Pleistocene epoch.