Although the racial system appears fixed and rigid, there was some fluidity within it, and racial domination of whites was not complete. Since the indigenous population of New Spain was so large, there was less labor demand for expensive black slaves than other parts of Spanish America.  In the late eighteenth century the crown instituted reforms that privileged Iberian-born Spaniards (''peninsulares'') over American-born (''criollos''), limiting their access to offices. This discrimination between the two became a sparking point of discontent for white elites in the colony.