living off the dry grasses of the area. Settlers later came and started capturing horses for riding and use as pack animals. The Native Americans had already been doing that many years before. Throughout the 19th century, a large proportion of the horses were crossed with imported European Thoroughbred, coach, and draft horse stallions, and a larger, coarser, long-striding multi-purpose, saddle-cart horse resulted. However, the crossbreeding nearly ruined the native Spanish horse type. In 1918, the Argentine breeders decided to create a purebred criollo registry, and the breeders' association was then formed in 1923. Much infighting occurred between Emilio Solanet and Enrique Crotto's groups. The first promoted the Asian-type crioulo and the latter the taller African type with a coarse, convex head; fallen croup; and thinner mane and tail. It was not until 1934 that Dr. Solanet was able to firmly take control of the breeders association. He set a new goal for the breed with a shorter, more compact stock horse which emulated the Chilean Horse breed that he admired so much. In 1938, 70% of the registered crioulos were culled because they did not possess the phenotype desired by Dr. Solanet and his followers. The new breed standard, about which he had written in 1928, was finally made available to the public once he was assured that the breeders were more united in their breed objectives. It would not be until 1957 that the registry was closed for Argentine native breeds, but the registry has remained open for the Chilean Horse breed that has been so influential in giving shape to the crioulo as a better stock horse. Nevertheless, the breed maintains its own identity in a taller, leggier and squarer body conformation with a more angular hock that gives it the long stride it requires to cover the great distances in the flat Argentine plains known as "Pampas". The modern crioulo head has a straight facial profile and a shorter muzzle with longer ears than is typical in the Chilean Horse breed. Endurance The breeders implemented rigorous endurance tests to help evaluate horses for breeding. In these events known as , the horses are ridden over a 750 km (466 mi) course to be completed in 75 hours split into 14 days. No supplemental feed is allowed. The horses are required to carry heavy loads of 245 lb (110 kg) on their backs and may only eat