 After the endurance race from Ashkabad to Moscow in 1935, when the purebreds finished in much better condition than the part-breds, the studbook management decided to consider all crossbred horses born after 1936, as not purebred.Horses with English Thoroughbred ancestors born prior to that date were allowed to remain inside the studbook (e.g.044 Tillyakush, grandson of Thoroughbred Burlak, 831 Makh, granddaughter of Thoroughbred Blondelli and great-great-granddaughter of Thoroughbred Junak, and line founder 9 Ak Belek, a direct descendant in the male line of the Thoroughbred stallion Fortingbrass).