. 0   ° C , ▁and ▁lowest ▁in ▁January , ▁at ▁around ▁ 0 . 1   ° C . ▁ ▁History ▁K ō ri y ama ▁origin ated ▁as ▁a ▁regional ▁government al ▁center ▁in ▁the ▁N ara ▁period , ▁when ▁the ▁area ▁was ▁on ▁the ▁front ier ▁of ▁Yam ato ▁settlement ▁of ▁the ▁T ō h oku ▁region . ▁The ▁surrounding ▁area ▁developed ▁into ▁sh ō en ▁controlled ▁by ▁various ▁sam ur ai ▁cl ans ▁in ▁the ▁He ian ▁and ▁Kam ak ura ▁periods . ▁Near by ▁cent ers , ▁such ▁as ▁N ih on m ats u ▁developed ▁into ▁castle ▁towns , ▁K ō ri y ama ▁remained ▁as ▁a ▁commercial ▁center ▁and ▁th riv ed ▁as ▁a ▁post ▁town ▁because ▁of ▁its ▁importance ▁as ▁a ▁traffic ▁foc al ▁point ▁into ▁the ▁E do ▁period ▁and ▁was ▁part ▁of ▁the ▁territory ▁of ▁N ih on m ats u ▁Domain . ▁ ▁With ▁the ▁establishment ▁of ▁the ▁modern ▁municipal ities ▁system ▁on ▁April ▁ 1 , ▁ 1 8 8 9 , ▁the ▁town ▁of ▁K ō ri y ama ▁was ▁established ▁within ▁As aka ▁District . ▁ ▁In ▁the ▁early ▁Me iji ▁period , ▁many ▁dispos s essed ▁sam ur ai ▁were ▁assigned ▁und e velop ed ▁lands ▁in ▁the ▁area ▁to ▁rec laim ▁and ▁as ▁a ▁result , ▁the ▁population ▁grew ▁and ▁region ▁developed ▁into ▁an ▁agricult ural ▁center . ▁The ▁relative ▁abund ance ▁of ▁hydro elect ric ▁power ▁also ▁helped ▁with ▁the ▁development ▁of ▁local ▁industry .