Oviedo says that the sweet potato “came with that evil lot of Negroes and it has taken very well and it is profitable and good sustenance for the Negroes of whom there is a greater number than is necessary on account of their rebellions.”[42] In the same way maize and sugar cane may have been imported from Africa. Further than this the raising of bread roots, manioc, yam and sweet potatoes may have come to America from Guinea by way of Brazil. From Brazil the culture of these crops spread and many of the words referring to them are of undoubted African origin. Negroes probably reached the eastern part of South America from the West Indies while others from the same source went north along the roads marked by the Mound Builders as far as Canada. “The chief cultural influence of the Negro in America was exerted by a Negro colony in Mexico, most likely from Teotihuacan and Tuxtla, who may have been instrumental in establishing the city of Mexico. From here their influence pervaded the neighboring tribes and ultimately, directly or indirectly, reached Peru.”[43] The mounds of the “Mound Builders” were probably replicas of Negro forts in Africa. “That this tendency to build forts and stockades proceeded from the Antilles, whence the Arawaks had come in the beginning of the sixteenth century, is proved by the presence of similar works in Cuba. These are found in the most abandoned and least-explored part of the island and there can be little doubt that they were locations of fugitive Negro and Indian stockades, precisely such as were in use in Africa. It is not possible to prove the direct participation of the Negroes in the fortifications of the North American Indians, but as the civilizing influence on the Indians to a great extent proceeded from Cuba over Florida towards the Huron Country in the north, the solution of the question of the Mound Builders is to be looked for in the perpetuation of Arawak or Carib methods, acquired from the Negroes, as well attested by Ovando’s complaint in 1503 that the Negroes spoiled the manners of the Indians; and transferred to the white traders, who not only adopted the methods of the Indians, but frequently lived among the Indians as part of them, especially in Brazil where we have ample documentary evidence of the fact.”[44] All this is prehistoric and in part conjectural and yet it seems reasonable to suppose that much in custom, trade and religion which has been regarded as characteristic of the American Indian arose from strong Negro influences of the pre-Columbian period. After the discovery of America by Columbus many Negroes came with the early explorers. Many of these early black men were civilized Christians and sprung from the large numbers of Negroes imported into Spain and Portugal during the fifteenth century, where they replaced as laborers the expelled Moors. Afterward came the mass of slaves brought by the direct African slave trade.