] An earlier study using amplified fragment length polymorphism (AFLP) fingerprinting showed a close association of wisent and American bison and probably with yak, but noted that the interbreeding of Bovini species made determining relationships problematic. [ 21 ] "Last of the Canadian Buffaloes", 1902, photograph: Steele and Company The steppe bison ( Bison priscus ) diverged from the lineage that led to cattle ( Bos taurus ) approximately 2 to 5 million years ago. The bison genus is clearly in the fossil record by 2 million years ago. [ 22 ] The steppe bison spread across Eurasia and was the bison that was pictured in the ancient cave paintings of Spain and Southern France The European bison or wisent arose from the steppe bison, without fossil evidence of other ancestral species between the steppe bison and the European bison, though the European bison might have arisen from the lineage that led to American bison if that lineage backcrossed with the steppe bison. Again, the web of relationships is confusing, but there is some evidence that the European bison is descended from bison that had migrated from Asia to North America, and then back to Europe, where they crossbred with existing steppe bison. [ 22 ] At one point, some steppe bison cross bred with the ancestors of the modern yak. After that cross breeding, a population of steppe bison ( Bison priscus ) crossed the Bering Land Bridge to North America . There is evidence of multiple crossings of