Here's a little bit more to stir into the pot:

Islam and Muslims were not new to the Americas. Columbus' idea, the theory that the earth is round, had been elaborated by Muslims, who had measured the earth's circumference seven hundred years before Columbus. In 1312, Mansa Abu Bakr of Mali is believed to have traveled from the Sengambian region of the African coast to the Gulf of Mexico. This account, which has recently captured the attention of scholars in Britain and America, comes to us by the way of al-Omari, a Muslim historian whose work shed much light on medieval African kingdoms in the sub-Saharan.