▁to ▁in ▁case ▁of ▁any ▁transaction . ▁The ▁lists ▁of ▁far ml ands ▁– ▁whether ▁private ▁or ▁government al ▁– ▁were ▁kept ▁at ▁the ▁tax ▁department . ▁During ▁this ▁period ▁there ▁were ▁some ▁official ▁r ul ings ▁on ▁q an ats , ▁streams , ▁construction ▁of ▁dam , ▁operation ▁and ▁maintenance ▁of ▁q an ats , ▁etc . ▁The ▁government ▁proceeded ▁to ▁repair ▁or ▁d red ge ▁the ▁q an ats ▁that ▁were ▁abandoned ▁or ▁destroyed ▁for ▁any ▁reason , ▁and ▁construct ▁the ▁new ▁q an ats ▁if ▁necessary . ▁A ▁document ▁written ▁in ▁the ▁P ah la vi ▁language ▁pointed ▁out ▁the ▁important ▁role ▁of ▁q an ats ▁in ▁developing ▁the ▁cities ▁at ▁that ▁time . ▁In ▁Iran , ▁the ▁advent ▁of ▁Islam , ▁which ▁coinc ided ▁with ▁the ▁over throw ▁of ▁the ▁S ass an id ▁dynast y , ▁brought ▁about ▁a ▁prof ound ▁change ▁in ▁religious , ▁political , ▁social ▁and ▁cultural ▁structures . ▁But ▁the ▁q an ats ▁stayed ▁int act , ▁because ▁the ▁economic ▁infrastr ucture , ▁including ▁q an ats ▁was ▁of ▁great ▁importance ▁to ▁the ▁Arab s . ▁As ▁an ▁instance , ▁M . ▁Lomb ard ▁reports ▁that ▁the ▁Mos lem ▁cler ics ▁who ▁lived ▁during ▁Abb as id ▁period , ▁such ▁as ▁A bo o yo ose f ▁Ya ’ q o ob ▁( de ath ▁ 7 9 8 ▁AD ) ▁st ip ulated ▁that ▁who ever ▁can ▁bring ▁water ▁to ▁the ▁idle ▁lands ▁in ▁order ▁to ▁cultiv ate , ▁his ▁tax ▁would ▁be