Tarpan (Equus ferus ferus, also known as Eurasian wild horse) is an extinct subspecies of wild horse. The last individual believed to be of this subspecies died in captivity in Russia in 1909, although some sources claim that it was not a genuine wild horse due to its resemblance to domesticated horses.
Beginning in the 1930s, several attempts were made to develop horses that look like the Tarpan through selective breeding, called breeding back by advocates. The breeds that resulted included the Heck horse, the Hegardt or Stroebel's horse, and a derivation of the Konik breed, all of which have a primitive appearance, particularly in having the grullo coat color. Some of these horses are now promoted as "Tarpans."
Read more about Tarpan: Name and Etymology, Taxonomy, History, Appearance, The "breeding Back" Controversy