strains is the older one, and both trace to the Roman era, far earlier than the Muslim conquest of Spain that is commonly assumed to mark the beginning of such crossbreeding. At one time, the northern Celtic horses were though to have ancestry related to the Exmoor pony of the British Isles, but subsequent Mitochondrial DNA studies revealed that the populations are not closely related until there was some documented admixture between Exmoors and Celtic horses in the early-to-mid 20th century. If anything, the Iberian breeds are characterized by a "consistent absence of geographical structure". When the Spanish reached the Americas in the late 15th century, they brought various horses of Iberian ancestry with them. Their descendants have been designated as the Colonial Spanish Horse and have contributed significantly to a number of horse breeds in both North and South America. In modern times, stallions from outside breeds were crossed on local breeds, such as the Exmoor pony stallions brought to the area, or for example, the heavy Burguete and Jaca Navarra breeds crossed on foreign stallions to create a bigger animal more useful for the horsemeat industry. In Spain and Portugal, the 1980s marked the start of efforts to bring back several of the Northern Iberian breeds from extinction, some of which were down to a few dozen individuals. The Cartusian strain of Pure Spanish (Andalusian) horse was also endangered, with a breeding population of about 150 animals. In 2005, a distinctive primitive, feral breed was identified inside Doñana National Park, the Retuerta horse (Caballo de las retuertas). See also List of Iberian horse breeds Sable Island horse References External links Report on DNA of Spanish horses Info on Jaca Navarra (Spanish) (Google translation) Types of horse Iberian Peninsula