Umor was the ruler of Bulgaria

Bulgaria

Bulgaria , officially the Republic of Bulgaria , is a parliamentary democracy within a unitary constitutional republic in Southeast Europe. The country borders Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, as well as the Black Sea to the east...

 in 766.

According to the Namelist of Bulgarian Rulers, Umor reigned for only 40 days in 766 and belonged to the Ukil

Uokil

Uokil is one of Yuezhi tribes, defeated and displaced by the Hun's expansion in the 2nd century BC. Uokil may have been one of the two Yuezhi dynastic tribes. Traces of ethnonym "Uokil" are found in the East Mongolia and Manchuria territories in the Syanbi Uokil (Ukil, Vokil, Augal) is one of...

 clan, which makes him a relative of the former rulers Vinekh

Vinekh of Bulgaria

Vinekh was ruler of Bulgaria in the mid-8th century.According to the Namelist of Bulgarian Rulers, Vinekh reigned for 7 years and was a member of the Uokil clan . According to the chronology developed by Moskov, Vinekh would have reigned 754–762...

 and possibly Kormisosh

Kormisosh of Bulgaria

Kormisosh was a ruler of Bulgaria during the 8th century.The Namelist of Bulgarian Rulers states that he belonged to the Ukil clan and ruled for 17 years. According to the chronology developed by Moskov, Kormisosh would have reigned from 737 to 754...

. The Byzantine sources indicate that his predecessor Sabin

Sabin of Bulgaria

Sabin was the ruler of Bulgaria from 765 to 766.Some scholars think that Sabin was omitted from the Namelist of Bulgarian Rulers because he was a Slav, but his name could indicate Latin or even Iranian origins. He was related by marriage to Kormisosh, who was either a father-in-law or a...

 entrusted Bulgaria to Umor, but give no details of his short reign or fate. Some scholars speculate that he was a champion of the peace party like his discredited predecessor, and that he may have likewise fled to the Byzantine Empire

Byzantine Empire

The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

.

The 17th century Volga Bulgar compilation Ja'far Tarikh (a work of disputed authenticity) represents Yumart (i.e., Umor) as the elderly father-in-law of the former ruler Teles (i.e., Telets

Telets of Bulgaria

Telets was the ruler of Bulgaria from 762 to 765.According to the Namelist of Bulgarian Rulers, Telets reigned for 3 years "instead of another", and he was a member of the Ugain clan. This is corroborated by the Byzantine sources, which indicate that Telets replaced the legitimate rulers of...

). According to this source Yumart deposed Sain (i.e., Sabin) and died shortly afterwards.