▁ 9 th ▁century , ▁the ▁Pers ian ▁math ematic ian ▁and ▁ge ograph er , ▁Hab ash ▁al - Has ib ▁al - Mar w azi , ▁employed ▁spher ical ▁trig on ometry ▁and ▁map ▁projection ▁methods ▁in ▁order ▁to ▁convert ▁polar ▁coordinates ▁to ▁a ▁different ▁coordinate ▁system ▁cent red ▁on ▁a ▁specific ▁point ▁on ▁the ▁sphere , ▁in ▁this ▁the ▁Q ib la , ▁the ▁direction ▁to ▁Me cca . ▁Ab ū ▁Ray h ā n ▁B ī r ū n ī ▁( 9 7 3 – 1 0 4 8 ) ▁later ▁developed ▁ideas ▁which ▁are ▁seen ▁as ▁an ▁anticip ation ▁of ▁the ▁polar ▁coordinate ▁system . ▁Ar ound ▁ 1 0 2 5 , ▁he ▁describes ▁a ▁polar ▁equ i - az im uth al ▁equ id istant ▁projection ▁of ▁the ▁cel est ial ▁sphere . ▁However , ▁this ▁type ▁of ▁projection ▁had ▁been ▁used ▁in ▁ancient ▁Egypt ian ▁star - maps ▁and ▁was ▁not ▁to ▁be ▁fully ▁developed ▁until ▁the ▁ 1 5 ▁and ▁ 1 6 th ▁centuries . ▁ ▁In ▁the ▁early ▁ 1 0 th ▁century , ▁Ab ū ▁Z ay d ▁al - B alk h ī , ▁originally ▁from ▁B alk h , ▁founded ▁the ▁" B alk h ī ▁school " ▁of ▁terrest rial ▁mapping ▁in ▁Bag hd ad . ▁The ▁ge ograph ers ▁of ▁this ▁school ▁also ▁wrote ▁extens ively ▁of ▁the ▁pe op les , ▁products , ▁and ▁custom s ▁of ▁areas ▁in ▁the ▁Muslim ▁world , ▁with ▁little ▁interest