Omurtag was a Great Khan (Kanasubigi) of Bulgaria from 814 to 831. He is known as "the Builder". In the very beginning of his reign he signed a 30-year peace treaty with the neighboring Eastern Roman Empire which remained in force to the end of his life. Khan Omurtag successfully coped with the aggressive policy of the Frankish Empire to take Bulgaria's north-western lands and suppressed the unrest among several Slavic tribes. He made administrative reforms which increased the power and the authority of the central government. His reign was marked with a strong development of Bulgarian architecture with a number of significant construction projects.

Khan Krum , often referred to as Krum the Fearsome was the Khan of Bulgaria from sometime between 796 and 803 until his death in 814. During his reign the Bulgarian territory doubled in size, spreading from the middle Danube to the Dnieper and from Odrin to the Tatra Mountains. His able and energetic rule brought law and order to Bulgaria and developed the rudiments of state organization.