Omurtag (or Omortag) also known as Murtag or Murtagon (Bulgarian: Омуртаг; Greek: Μορτάγων[1] and Ομουρτάγ[2]) was a Great Khan (Kanasubigi)[3] of Bulgaria from 814 to 831.

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.

The historians usually accept as a compromise the view of Professor Vasil Gyuzelev that Omurtag succeeded his father after short disturbances in the government.

In the ensuing battle near the town of Burtodizos (probably the modern Babaeski) the Byzantines were victorious - Omurtag escaped the battlefield on his swift horse.

Those considerations gave reason for Omurtag to conclude a 30-year peace treaty with the Byzantines in 815, which was partly inscribed on a surviving column found near the village of Seltsi, Shumen Province.

Khan Omurtag sent an army to help Michael II put down the rebellion which attacked the rebels at the Battle of Kedouktos (winter 822 or spring 823).

In 818 the Slavic tribes of the Timočani, Abodrites, and Braničevci (who inhabited the lands along the middle Danube, former Avar domains) rebelled against the increasingly centralized Bulgarian suzerainty in the west and sought the support of the Frankish Emperor Louis the Pious.

Failing to gain Frankish co-operation, Omurtag issued an ultimatum in 826 and in 827 sent a fleet along the Danube and the Drava, which restored Bulgarian control over portions of southeastern Pannonia.

The problems in that case were the attempts of several Slavic tribes to gain more autonomy which was at variance to the Bulgarian policy of centralization and incorporation of the Slavs.

Another memorial inscription, for kopan Okorsis who drowned in the Dneper, testifies to military activities along the north-eastern border dating as early as 824.

Although there is no direct evidence for the outcome of the war, it can be assumed that it ended with a Bulgarian victory due to the swift and energetic precautions taken by Omurtag.

He made an administrative reform and divided the state into large provinces called comitati (singular comitat) whose governors were directly appointed by the Kanasubigi and had both military and civil authority.

Omurtag pursued a policy of repression against Christians, particularly the Byzantine prisoners of war settled by his father Krum in Bulgaria (mostly north of the Danube).

The 17th century Volga Bulgar compilation Ja'far Tarikh (a work of disputed authenticity) represents Amurtag or Yomyrčak (i.e., Omurtag) as the son of Korym (i.e., Krum).