▁of ▁all ▁kinds ”. ▁ ▁For ▁a ▁society ▁to ▁be ▁considered ▁a ▁slave ▁society ▁there ▁would ▁need ▁to ▁be ▁at ▁“ 3 0 % ▁of ▁the ▁population ▁as ▁slaves , ▁and ▁slave ▁labor ▁had ▁to ▁account ▁for ▁a ▁major ▁proportion ▁of ▁that ▁society ’ s ▁production ’ . ▁ ▁So ▁in ▁the ▁time ▁frame ▁of ▁the ▁Roman ▁times ▁to ▁the ▁Middle ▁A ges ▁the ▁percentage ▁of ▁the ▁slave ▁population ▁were ▁minimal . ▁“ s la ves ▁probably ▁made ▁up ▁less ▁than ▁ 1 ▁percent ▁of ▁the ▁population ▁in ▁Spain ”. ▁“ S la very ▁was ▁cross ▁cultural ▁and ▁multi - eth nic ” ▁ ▁in ▁addition ▁to ▁that , ▁sla very ▁played ▁an ▁important ▁role ▁in ▁the ▁development ▁of ▁the ▁economy ▁for ▁Spain ▁and ▁other ▁countries . ▁ ▁Roman ▁laws ▁ ▁The ▁idea ▁that ▁sla very ▁was ▁based ▁on ▁race ▁was ▁and ▁continues ▁to ▁be ▁one ▁of ▁the ▁biggest ▁mis con ception s ▁about ▁sla very ▁in ▁Spain . ▁Phill ips ▁Jr . ▁William ▁D . ▁in ▁The ▁History ▁of ▁S la very ▁in ▁I ber ia , ▁challeng ed ▁the ▁idea ▁that ▁race ▁was ▁not ▁the ▁key ▁to ▁determine ▁who ▁was ▁ens la ved , ▁but ▁instead ▁religion . ▁Roman ▁laws ▁existed , ▁sub j ug ating ▁sla very ▁which ▁included ▁the ▁sources ▁of ▁slaves , ▁their ▁conditions , ▁and ▁possibility ▁of ▁liber ation . ▁In ▁addition , ▁the ▁" normal ▁pattern " ▁was ▁to ▁prohib it ▁people ▁from ▁ens la ving ▁someone ▁within ▁their ▁same ▁religion . ▁Muslim s ▁could ▁not