Below Omurtag (814 831, the southern Black Beach as much as Debelt was acknowledged as Bulgarian. That occurred in 815 with the signing of the 30-year peace treaty with Byzantium. The success of the Black Sea route of Bulgarian coverage was thus legalized.
After the stabilization of the seaside border as much as Mount Strandzha, Kan Omurtag maintained the opposite essential orientation of his international coverage the orientation, began by Kan Krum, to the northwest in direction of the Slavs on the banks of Center Danube, who had been separated from Bulgaria by the Empire of the Franks. That is how the contemporaries perceived it (in accordance with the so-called Fulden Chronicles — The Lifetime of Charlemagne by Einhard):
In 827, “the Bulgarians despatched troops in ships up the River Drava, plundered and burnt the land of the Slavs inhabiting Pannonia, drove away their kings and appointed Bulgarian governors”; in 829, “once more the Bulgarians got here in ships up the Drava, destroyed by hearth a few of our settlements close to the river”.
The Bulgarian “admiralty” of the interval is little doubt positioned in and recognized with the highly effective island fortress and port of modem Romanian Pakuiullui Soare Island that’s about 20 kilometers to the east of the Bulgarian fortress and port of Drustar (current Silistra). To this very day one can see the deep traces within the stone blocks of the quays on the island, left by the ropes with which they moored the ships.
The constructing of this fortress harbor as an “admiralty” is because of its distinctive political and army strategic location on Decrease Danube as an inside Bulgarian river. Drustar fortress harbor secured and guarded the direct connections of the capital Pliska, and later of Preslav to the Bulgarian lands to the north of the Danube, which stretched to the Carpathians.
As well as, along with Drustar, this island fortress harbor managed the commerce alongside the Danube and advantageously blocked the invasions of enemy (primarily Byzantine) fleets attempting to penetrate into the Danube from the Black Sea. That was carried out actively with ships and passively via lengthy chains lowered within the water, which linked the 2 riverbanks.
Kaliakra was one other essential fortress harbor on the north Black Beach of Bulgaria through the Seventh-Eighth-10th- 11th centuries. There the continuity between the Late Antiquity of Byzantium and the early medieval interval of Bulgaria is documented excellently. This fortress harbor performed a particularly essential army strategic and abroad commerce function for the Bulgarian state with its robust partitions, first-rate harbor space and quite a few all-purpose ships.