Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Criollo (in Spanish), or Crioulo (in Portuguese), is the native horse of Argentina (1918), Uruguay (1923), Brazil (1932) and Paraguay. It may have the best endurance of any horse breed in the world next to the Arabian. In fact, due to the criollo's low basal metabolism, it may be a better long-distance horse than the Arabian in prolonged races over a week in duration with no supplemental feed. The breed, known for its hardiness and stamina, is most popular in its home country. The word criollo originally referred to human and animals of pure-bred Spanish ancestry that were born in the Americas, or, in Portuguese crioulo, to animals or slaves born in the Americas. In time, the meaning of the word would simply come to refer to native breeds of the Americas.