ge ▁of ▁S irm ium ▁in ▁ 5 8 0 – 5 8 2 ▁was ▁a ▁decis ive ▁event ▁in ▁the ▁history ▁of ▁the ▁B alk ans . ▁The ▁fall ▁of ▁the ▁city ▁to ▁the ▁Av ars ▁dep riv ed ▁the ▁By z antine ▁Empire ▁of ▁its ▁major ▁strong hold ▁on ▁the ▁north western ▁Dan ube , ▁opening ▁the ▁path ▁for ▁dev ast ating ▁inc urs ions ▁by ▁the ▁Av ars ▁and ▁their ▁S lav ic ▁al lies ▁into ▁the ▁B alk ans . ▁ ▁S irm ium , ▁which ▁for ▁much ▁of ▁the ▁ 6 th ▁century ▁had ▁been ▁controlled ▁by ▁the ▁Goth s ▁and ▁then ▁the ▁G ep ids , ▁had ▁come ▁under ▁By z antine ▁control ▁in ▁ 5 6 7 ▁after ▁the ▁Lomb ard – G ep id ▁War ▁( 5 6 7 ). ▁The ▁Av ars ▁appeared ▁along ▁the ▁Dan ube ▁at ▁about ▁the ▁same ▁time . ▁They ▁launched ▁a ▁first ▁attack ▁on ▁S irm ium ▁in ▁ 5 6 8 , ▁but ▁were ▁seen ▁off ▁by ▁the ▁local ▁governor , ▁Bon us . ▁The ▁By z ant ines ▁secured ▁peace ▁with ▁the ▁Av ars ▁through ▁the ▁payment ▁of ▁an ▁annual ▁t ribute , ▁which ▁by ▁ 5 7 8 ▁had ▁ris en ▁to ▁some ▁ 8 0 , 0 0 0 ▁solid i . ▁In ▁ 5 8 0 , ▁however , ▁the ▁A var ▁k h agan , ▁Bay an ▁I , ▁march ed ▁with ▁his ▁men ▁to ▁the ▁right ▁bank ▁of ▁the ▁S ava ▁river