Moriscos were bound by debt obligations, not physical chains, before 1570

Evidence

These crypto- Muslims might, under the Mudejar status, which most of their forebears had had in the Middle Ages (and which continued until the 1520s in the lands of Aragon), effectively be debt slaves, tied to the land by obligations set at levels they were unable to meet, but the mechanisms that kept them in subservience were rents and dues rather than shackles and chains. — L. P. Harvey, Muslims in Spain, 1500 to 1614, 1138