Two purebred animals of different breeds produce a crossbreed, and crossbred plants are called hybrids. Taurus cattle is a breed that is still being crossbred and bred selectively. Most current bison herds are genetically polluted or partly crossbred with cattle. Most current herds, however are genetically polluted or partly crossbred with cattle. It has been crossbred extensively with "Bos taurus taurus" (European) beef breeds of cattle. Irish Draughts are commonly crossbred with Thoroughbreds and Warmbloods to produce high-quality sport horses. In Nepal, Tibet and Mongolia, domestic cattle are crossbred with yaks. Clearfield is also crossbred with higher yielding varieties to produce an overall hardier plant. He also crossbred the bison with domestic cattle, which he called cattalo. In India, Nepal, Tibet, and Mongolia, cattle are crossbred with yaks. Polonceau crossbred the cashmeres with Angora goats to improve the down for spinning and weaving. Some Curlies have been crossbred to gaited horses. Beef and bison were first intentionally crossbred during the mid-19th century. This breed was also crossbred with Boerboels in the region. At one point, some steppe bison crossbred with the ancestors of the modern yak.