You don't need to give credence to the Afrocentrists' claims to believe that there was much more contact between the Old and New Worlds before Columbus than is generally known.
The evidence is all around North America: Mystery Hill in New Hampshire, the Newport Tower, the Westford rock etchings, castle ruins in New Ross, Nova Scotia; Prince Henry Sinclair's discovery of Nova Scotia and the Micmac Indians' legends of Glooscap; St. Brendan's Navigatio, the Kensington (MN) stone, the Beardmore (ON) Viking relics; the Melungeons, Chinese descriptions of the Grand Canyon and Arizona deserts; Johannes Scolvuss; etc. etc.
Don’t forget the forbidden caves in the Grand Canyon (forbidden by US Govt.)