d were generally used for skilled or semi-skilled labor, were granted many the same rights as serfs or indentured servants, could often earn their freedom by conversion to the master's religion (Christian or Muslim as the case so dictated), and had as many opportunities, if not more, to purchase their freedom as serfs had to buy free of their bondage to the land.
The Age of Exploration changed that status quo with the "discovery" by Portuguese explorers/entrepreneurs of the trade value of supplying Sub-Saharan Africans to their Spanish cousins in the New World. It seems the Spanish conquistadors were discovering several unpleasant things about their rapidly-acquired possessions, not the least being that - with the exception of quickly gathered-and-spent hoards of Incan and Aztec wealth - the profits from Central, South and Caribbean America would have to be earned via hard manual labor. It is not the conqueror's natural bent to put his back to the plow when there is a defeated population to exploit; within months of each conquest, the Spanish had organized their Indio subjects into required-work battalions that resembled slavery in all but the most crucial aspect - the Indios being ostensibly "free," their masters were not required to provide for them in any way save that of supplying religious instruction for the Indios' conversion to the righteous ways of Roman Catholicism. The Indios, however, did not handle the Spaniards' oppression well: they developed an amazing tendency to die in large amounts from the onerous physical demands placed upon them and from the smallpox and other European diseases the conquerors brought across the Atlantic. Thus in Hispaniola and Cuba, less than twenty years after Columbus' discovery of the West Indies and even before Cortes' first incursions into Mexico, the Spanish landlords of the New World were finding it necessary to import Portuguese-supplied Sub-Saharan slaves to fill out the dwindlin...