Of course, there would also be other markers. Fertilizers is one. Another is the plants and animals they used for food. Why are some plants and animals still i

Of course, there would also be other markers. Fertilizers is one. Another is the plants and animals they used for food. Why are some plants and animals still indigenous to certain areas, assuming there was a small globe spanning civilization at some point in the last million or so years? Shouldn't this civilization have at least brought the crops and livestock to other areas of the globe they visited?