Some historians and political observers were surprised over the weekend when Turkish President Recep Tayyip Erdogan, chief of America’s NATO ally, said Muslims discovered the Americas more than 300 years before Christopher Columbus. But the Islamic leader was doing nothing more than stating publicly what Islamic historians have said, including some who believe Native Americans who spoke Arabic greeted Muslim adventurers hundreds of years before the Nina, Pinta and Santa Maria sailed. Among those reporting Erdogan’s statement was the BBC, which noted his AK Party “is rooted in political Islam.” Erdogan said, “Muslim sailors arrived in America in 1178,” but...