Answer:
Europe immediately upon arrival, European alleles began to flow, admixed into the indigenous population, and that process has continued ever since: European DNA is found today throughout the Americas, no matter how remote or isolated a tribe might appear to be. But before Columbus, these continents were already populated. The indigenous people hadn’t always been there, nor had they originated there, as some of their traditions state, but they had occupied these American lands for at least 20,000 years.