Original sentence: It has been suggested that the 681 peace treaty with the Byzantine Empire that established the new state was concluded at Varna, and that the first Bulgarian capital may have been provisionally located in its vicinity before it moved to Pliska 70 km to the west
Edited sentence: It has been suggested that the 681 peace treaty with the Byzantine Empire that established the new state was concluded at Varna and that the first Bulgarian capital south of the Danube may have been provisionally located in the vicinity—possibly in a city near Lake Varna's north shore named Theodorias (Θεοδωριάς) by Justinian I"—before it moved to Pliska 70 km to the west