Spanish explorers traveled to North and South America during the 16th century, seeking riches, new lands, and sometimes wilder dreams. They brought horses from Spain, hearty beasts that could carry a man long distances at speed. Horses sometimes became lost or were left behind or even ran away. Eventually, the wild horses became known as mustengo, meaning ownerless beast. Today, nearly 500 years later, a quarter million mustangs now roam the west in large herds, mostly occupying 30 million acres of federal land. Their name, then, applies partially to the breed, but more to their status: wild descendants of the original horses brought across the Atlantic by Spanish explorers.