▁of ▁the ▁Tang ▁period ▁was ▁J ia ▁Dan ▁( 7 3 0 – 8 0 5 ), ▁whom ▁Emperor ▁Dez ong ▁of ▁Tang ▁entr usted ▁in ▁ 7 8 5 ▁to ▁complete ▁a ▁map ▁of ▁China ▁with ▁her ▁recently ▁former ▁in land ▁colon ies ▁of ▁Central ▁Asia , ▁the ▁massive ▁and ▁detailed ▁work ▁completed ▁in ▁ 8 0 1 , ▁called ▁the ▁H ai ▁Ne i ▁H ua ▁Y i ▁Tu ▁( Map ▁of ▁both ▁Chinese ▁and ▁Bar bar ian ▁Pe op les ▁within ▁the ▁( F our ) ▁Se as ). ▁The ▁map ▁was ▁ ▁and ▁ ▁in ▁dimension , ▁mapped ▁out ▁on ▁a ▁grid ▁scale ▁of ▁ ▁equal ing ▁ 1 0 0 ▁li ▁( unit ) ▁( the ▁Chinese ▁equivalent ▁of ▁the ▁mile / kil ometer ). ▁J ia ▁Dan ▁is ▁also ▁known ▁for ▁having ▁described ▁the ▁Pers ian ▁G ulf ▁region ▁with ▁great ▁detail , ▁along ▁with ▁l ighth ouses ▁that ▁were ▁ere cted ▁at ▁the ▁mouth ▁of ▁the ▁Pers ian ▁G ulf ▁by ▁the ▁medieval ▁Iran ians ▁in ▁the ▁Abb as id ▁period ▁( refer ▁to ▁article ▁on ▁Tang ▁D ynast y ▁for ▁more ). ▁ ▁Song ▁ ▁During ▁the ▁Song ▁D ynast y ▁( 9 6 0 – 1 2 7 9 ) ▁Emperor ▁Ta iz u ▁of ▁Song ▁ordered ▁Lu ▁Du os un ▁in ▁ 9 7 1 ▁to ▁update ▁and ▁' re - write ▁all ▁the ▁Tu ▁J ing ▁in ▁the ▁world ', ▁which ▁would ▁seem ▁to ▁be ▁a ▁da un ting ▁task ▁for ▁one