Kotrag Khan was the founder of Idil Bolgar. He was the son of Kubrat who left Great Bulgaria after the death of his father. His successors reached the lands of modern Tatarstan and established a state during 7-9 centuries and recognised Islam as the official religion in 922 AD during the visit of Baghdad khalifat ambassador Ibn Fazlan and remained independent up until the 14th century, when it was conquered by the Batu-khan hordes of Mongolic and Turkic people widely known as Mongol-Tatars. The country's capital was called "Bulgar" or "Great Bulgar". The Little Minaret in Bolghar For other uses, see Bulgaria (disambiguation). ... Kubrats Great Bulgaria and adjacent regions, c. ... In 632, Khan Kubrat united the Bulgars and formed a confederation of tribes, known as Great Bulgaria, or Bulgaria Magna, with a capital at the ancient city of Fanagoria. ... Republic of Tatarstan (Russian: ; Tatar: ) is a federal subject of Russia (a republic). ... For people named Islam, see Islam (name). ... Ahmad ibn-al-Abbas ibn Rashid ibn-Hammad ibn-Fadlan (Aḥmad ʿibn alʿAbbās ʿibn Rasẖīd ʿibn ḥammād ʿibn Fadlān أحمد ابن العباس... Tatars (Tatar: Tatarlar/ТаÑаÑлаÑ), sometimes spelled Tartar (more about the name), is a collective name applied to the Turkic speaking people of Eastern Europe and Central Asia. ...
In his last hours Kubrat wanted to tell his offspring—Bayan, Kotrag, Asparukh, Kuber and Altsek—not to sever the still tenuous link between the different Bulgarian tribes.
Kotrag went northwards, to the River Volga, while Asparukh, Kuber and Altsek went south to search for a land without oppressors.
They secretly arranged it with Houba to send her word by a golden thread tied to the leg of a bird, whenever they were able to find a free land.