The region of Duklja (Dioclea) stretched along the Adriatic coast from Bay of Kotor to the mouth of the Drin river, excluding the major seaside towns like Lezhë, Ulcinj and Bar, which remained under the Byzantine rule. It occupied the central regions of Zeta nad Morača, and, like Travunija and Zachlumia, on its northern, mountainous side, leaned on the central Serbian state under the Vlastimirović dynasty, referred to as the Baptized Serbia by Constantine VII Porphyrogenitus. On the south, it bordered the Byzantine Empire in the direction of Dyrrachium, a Slavic/Serbian-Byzantine border which constantly changed for several centuries.