Earliest Europeans In North America, Speculation

How the earliest European arrivals dealt with the sophisticate peoples of the Hopewell system interest es me. How early did significant culture interaction and exchange occur between Hopewell people and perhaps even Adena people and Europeans? Certainly some arrived in the decades around the time of Columbus's explorations. Some very probably before that. Europeans were in North America before Jamestown and Plymouth and some may have looked over the area we now call Kentucky and may be the source of that name. The earliest Europeans to come into the new land did not come in overwhelming numbers or with overwhelming weapons so they would have had to deal with Native Peoples on a more nearly equal basis than the did at later times.

I've heard rumors of Welsh and Irish cultural and linguistic artifacts found among Indian peoples. Must be some interesting stories there.