▁" central " ▁or ▁" middle ", ▁and ▁gu ó ▁(/ ), ▁representing ▁" state " ▁or ▁" states "; ▁in ▁contemporary ▁usage , ▁" n ation ". ▁Prior ▁to ▁the ▁Q in ▁un ification ▁of ▁China ▁" Z h ong gu o " ▁referred ▁to ▁the ▁" Cent ral ▁States "; ▁the ▁con notation ▁was ▁the ▁prim acy ▁of ▁a ▁cult ur ally ▁distinct ▁core ▁area , ▁centered ▁on ▁the ▁Y ellow ▁River ▁valley , ▁as ▁distinguished ▁from ▁the ▁trib al ▁peri ph ery . ▁In ▁later ▁periods , ▁however , ▁" Z h ong gu o " ▁was ▁not ▁used ▁in ▁this ▁sense . ▁D yn astic ▁names ▁were ▁used ▁for ▁the ▁state ▁in ▁Imperial ▁China ▁and ▁concepts ▁of ▁the ▁state ▁aside ▁from ▁the ▁r uling ▁dynast y ▁were ▁little ▁understood . ▁R ather , ▁the ▁country ▁was ▁called ▁by ▁the ▁name ▁of ▁the ▁dynast y , ▁such ▁as ▁" H an ▁dynast y " ▁( H an cha o ▁), ▁" T ang ▁dynast y " ▁( T ang cha o ▁), ▁" The ▁Great ▁M ing " ▁( D aming ▁), ▁" The ▁Great ▁Q ing " ▁( Da q ing ▁), ▁as ▁the ▁case ▁might ▁be . ▁Until ▁the ▁ 1 9 th ▁century ▁when ▁the ▁international ▁system ▁came ▁to ▁require ▁a ▁common ▁legal ▁language , ▁there ▁was ▁no ▁need ▁for ▁a ▁fixed ▁or ▁unique ▁name . ▁ ▁There ▁were ▁ ▁different ▁us ages ▁of ▁the ▁term ▁" Z h ong gu o " ▁in ▁every ▁period .