▁ ▁Middle ▁A ges ▁ ▁The ▁town ▁has ▁been ▁fort ified ▁since ▁the ▁early ▁Middle ▁A ges , ▁when ▁Emperor ▁Justin ian ▁built ▁a ▁for tr ess ▁above ▁As cri vi um ▁in ▁ 5 3 5 , ▁after ▁exp elling ▁the ▁Ost rog oth s . ▁As cri vi um ▁was ▁pl under ed ▁by ▁the ▁Sar ac ens ▁in ▁ 8 4 0 . ▁It ▁was ▁further ▁fort ified ▁towards ▁the ▁peak ▁of ▁Saint ▁Ivan ▁by ▁Const antine ▁VII ▁P orph y ro gen net os ▁in ▁the ▁ 1 0 th ▁century . ▁It ▁was ▁one ▁of ▁the ▁more ▁influ ential ▁Dal mat ian ▁city - states ▁of ▁roman ized ▁Il ly ri ans ▁ ▁throughout ▁the ▁early ▁Middle ▁A ges , ▁and ▁until ▁the ▁ 1 1 th ▁century ▁the ▁Dal mat ian ▁language ▁was ▁still ▁spoken ▁in ▁Kot or . ▁The ▁city ▁was ▁part ▁of ▁By z antine ▁Dal mat ia ▁in ▁that ▁period , ▁and ▁the ▁modern ▁name ▁of ▁Kot or ▁probably ▁origin ated ▁in ▁the ▁By z antine ▁name ▁for ▁the ▁town : ▁De k ater a ▁or ▁De k ader on . ▁ ▁In ▁ 1 0 0 2 , ▁the ▁city ▁suffered ▁damage ▁under ▁the ▁occupation ▁of ▁the ▁First ▁Bulgar ian ▁Empire , ▁and ▁in ▁the ▁following ▁year ▁it ▁was ▁c eded ▁to ▁D uk l ja ▁by ▁the ▁Bulgar ian ▁Ts ar ▁Sam uil . ▁D uk l ja , ▁or ▁Dioc lea , ▁was ▁a ▁v ass al ▁du chy ▁of ▁By