Pre-Columbian transoceanic contact theories

A long time ago, before people from Europe went to visit America, some people think that there may have been some contact between these two places. This is called pre-Columbian transoceanic contact. Some theories suggest that ancient people from places like Africa, Europe, or Asia might have sailed across the big oceans and visited America a long time ago. There are not many pieces of evidence to prove this theory, but some people believe that there are signs that show contact between these two places was possible. However, many people also think that these theories are not possible and that the explorers from Europe were the first to come to America.