Byzantine–Bulgarian treaty of 815

His son and successor Omurtag tried to continue Krum's aggressive policy but his campaign in 814 was stopped by the Byzantines.

The agreement envisaged that the Byzantine Emperor must vow according to the pagan Bulgarian customs and Omurtag's emissaries according to the Christian laws.

Bulgaria on the other hand also faced religious problems, as the growing number of Christians disturbed Omurtag: the Khan began anti-Christian persecutions, to which his eldest son Enravota also fell victim.

The Bulgarians also had to restore their economy following the bloody conflicts of the first decade of the century, while their capital Pliska still lay in ruins.

[5] True to his word, in 823 Omurtag relieved the siege of Constantinople by the rebel Thomas the Slav and defeated his army.