1 7 , ▁as ▁well ▁as ▁the ▁short - l ived ▁Trans c au cas ian ▁Democratic ▁Feder ative ▁Republic , ▁in ▁ 1 9 1 8 , ▁the ▁leading ▁Mus av at ▁government ▁adopted ▁the ▁name ▁" A zer ba ij an " ▁for ▁the ▁newly ▁established ▁A zer ba ij an ▁Democratic ▁Republic , ▁which ▁was ▁proc laimed ▁on ▁May ▁ 2 7 , ▁ 1 9 1 8 , ▁for ▁political ▁reasons , ▁even ▁though ▁the ▁name ▁of ▁" A zer ba ij an " ▁had ▁always ▁been ▁used ▁to ▁refer ▁to ▁the ▁adjacent ▁region ▁of ▁contemporary ▁north western ▁Iran . ▁Thus , ▁until ▁ 1 9 1 8 , ▁when ▁the ▁Mus av at ▁regime ▁decided ▁to ▁name ▁the ▁newly ▁independent ▁state ▁A zer ba ij an , ▁this ▁design ation ▁had ▁been ▁used ▁exclus ively ▁to ▁identify ▁the ▁Iran ian ▁province ▁of ▁A zer ba ij an . ▁ ▁History ▁ ▁Pre - I sl am ic ▁period ▁The ▁oldest ▁kingdom ▁known ▁in ▁Iran ian ▁A zer ba ij an ▁is ▁that ▁of ▁the ▁Man nea ▁who ▁ruled ▁a ▁region ▁south - east ▁of ▁Lake ▁U rm ia ▁cent red ▁around ▁modern ▁Sa qq ez . ▁The ▁Man ne ans ▁were ▁a ▁conf eder ation ▁of ▁Iran ian ▁and ▁non - I ran ian ▁groups . ▁According ▁to ▁Professor ▁Z ad ok : ▁ ▁The ▁Mann ae ans ▁were ▁conquer ed ▁and ▁absor bed ▁by ▁an ▁Iran ian ▁people ▁called ▁Mat ien i , ▁and ▁the ▁country ▁was