▁R usta ▁and ▁I bn ▁R ust e ), ▁was ▁a ▁ 1 0 th - century ▁Pers ian ▁expl orer ▁and ▁ge ograph er ▁born ▁in ▁R osta ▁district , ▁Is fah an , ▁Pers ia . ▁He ▁wrote ▁a ▁ge ographical ▁comp end ium ▁known ▁as ▁Book ▁of ▁P reci ous ▁Records . ▁The ▁information ▁on ▁his ▁home ▁town ▁of ▁Is fah an ▁is ▁especially ▁extensive ▁and ▁valuable . ▁I bn ▁R ust ah ▁states ▁that , ▁while ▁for ▁other ▁lands ▁he ▁had ▁to ▁depend ▁on ▁second - hand ▁reports , ▁often ▁acquired ▁with ▁great ▁difficulty ▁and ▁with ▁no ▁means ▁of ▁checking ▁their ▁ver acity , ▁for ▁Is fah an ▁he ▁could ▁use ▁his ▁own ▁experience ▁and ▁observations ▁or ▁statements ▁from ▁others ▁known ▁to ▁be ▁reliable . ▁Thus ▁we ▁have ▁a ▁description ▁of ▁the ▁twenty ▁districts ▁( ro sta q s ) ▁of ▁Is fah an ▁containing ▁details ▁not ▁found ▁in ▁other ▁ge ograph ers ' ▁works . ▁Conc ern ing ▁the ▁town ▁itself , ▁we ▁learn ▁that ▁it ▁was ▁perfectly ▁circular ▁in ▁shape , ▁with ▁a ▁circum ference ▁of ▁half ▁a ▁f ars ang , ▁walls ▁def ended ▁by ▁a ▁hundred ▁to wers , ▁and ▁four ▁gates . ▁ ▁Record ed ▁information ▁ ▁His ▁information ▁on ▁the ▁non - I sl am ic ▁pe op les ▁of ▁Europe ▁and ▁Inner ▁Asia ▁makes ▁him ▁a ▁useful ▁source ▁for ▁these ▁obsc ure ▁regions ▁( he ▁was ▁even ▁aware ▁of ▁the ▁existence ▁of ▁the ▁British ▁Is les ▁and ▁of ▁the ▁He pt archy