The article analyzes the information of the famous scientist of the 11th century. Abu Reyhan al-Biruni about the Volga Bulgaria, which are in his surviving works – “Monuments of past generations”, “Masudov’s tables on the astronomy of stars”, “Geodesy”, “The book of admonishment to the beginnings of the science of stars”, “Separation of speech about the problem of shadows”, “The Book of Information for the Knowledge of Jewels”, “India”. In these works, the adherence of the Bulgars to Islam is mentioned several times, which was especially emphasized by the author, despite the fact that this people lived far to the north, on the edge of the “inhabited land”. This northern location of the Volga Bulgaria and its localization among the seven climates were especially noted by al-Biruni. He specifically paid attention to the geographical coordinates of the two cities of Bulgaria, which, according to his ideas, were in the state of the Slavs (as-sakaliba). It is possible that this view was based on Ibn Fadlan's book about his journey to the Volga Bulgaria, although al-Biouni does not mention this event. The author also showed the position of the shores of this country among the seas of the Earth, pointing to a certain northern bay of the Surrounding Sea, which is in contact with the country of the Volga Bulgars. This information has different interpretations. Al-Biruni singled out the information of the Bulgars about trade with the northern peoples of the Isu and Yura. Al-Biruni was one of the first to inform about the trade relations of these peoples with the Bulgars, their methods of trade (“barter trade”) and their ways of moving on the snow. A unique evidence of the language spoken by the inhabitants of the Bulgar city of Suvar as a combination of Turkic and Khazar is revealed. Some of the messages cited by al-Biruni were obtained by him from the books of geographers of the 9th–10th centuries, but revised by the author in accordance with his own knowledge and ideas; some of the messages are original. The idea of our author about the cities and people of the Bulgars as the most remote people of the civilized world is emphasized by the fact that the Bulgars, unlike other nearby peoples (such as the Isu and Yura), are Muslims, which was repeatedly emphasized by him in different books. Despite the use of the books of his predecessors, al-Biruni showed that the Bulgars in his time were quite important in the international arena due to the Muslim religion and trade.