▁gener ations . ▁During ▁this ▁period , ▁the ▁technology ▁of ▁q an at ▁was ▁in ▁its ▁he yd ay ▁and ▁it ▁even ▁spread ▁to ▁other ▁countries . ▁For ▁example , ▁following ▁D arius ' s ▁order , ▁Sil aks ▁the ▁naval ▁commander ▁of ▁the ▁Pers ian ▁army ▁and ▁K hen omb iz ▁the ▁royal ▁architect ▁managed ▁to ▁construct ▁a ▁q an at ▁in ▁the ▁o asis ▁of ▁K har ag ha ▁in ▁Egypt . ▁B ead nell ▁bel ieves ▁that ▁q an at ▁construction ▁dates ▁back ▁to ▁two ▁distinct ▁periods : ▁they ▁were ▁first ▁constructed ▁by ▁the ▁Pers ian se , ▁and ▁later ▁the ▁Rom ans ▁d ug ▁some ▁other ▁q an ats ▁during ▁their ▁reign ▁in ▁Egypt ▁from ▁ 3 0 ▁BC ▁to ▁ 3 9 5 ▁AD . ▁The ▁magnific ent ▁temple ▁built ▁in ▁this ▁area ▁during ▁D arius ' s ▁reign ▁shows ▁that ▁there ▁was ▁a ▁considerable ▁population ▁depending ▁on ▁the ▁water ▁of ▁q an ats . ▁R ager z ▁has ▁estimated ▁this ▁population ▁to ▁be ▁ 1 0 , 0 0 0 ▁people . ▁The ▁most ▁reliable ▁document ▁confirm ing ▁the ▁existence ▁of ▁q an ats ▁at ▁this ▁time ▁was ▁written ▁by ▁Poly b ius ▁who ▁states ▁that : ▁“ the ▁streams ▁are ▁running ▁down ▁from ▁everywhere ▁at ▁the ▁base ▁of ▁Al bor z ▁mountain , ▁and ▁people ▁have ▁transferred ▁too ▁much ▁water ▁from ▁a ▁long ▁distance ▁through ▁some ▁sub ter rane an ▁can als ▁by ▁sp ending ▁much ▁cost ▁and ▁labor ”. ▁ ▁During ▁the ▁Sele uc id