http://kitap.net.ru/begunov/1.php  (In Russian)
A quick Google search for “Чулман толгау“(“Chulman Tolgau“) would bring up reviews and critiques, including for the following foreword.
Extraneous notes and comments are shown in blue. These comments reflect commentaries posted by PhD in history, Hermitage Sr. Scientist Z.A.Lvova http://zlatalvova.narod.ru/kritika/Begunov.htm , who generally finds the text of “Chulman Tolgau“being poorly served by the unsubstantiated foreword written by Akad. Yu.K.Begunov.

Djangi ibn Hakan al-Kimaki, whom Idrisi names among his sources (cf. Jaubert, i, p. xii) tells in the (now lost, and known only from Idrisi citations) "Description of Akbash and Balyndjar wonders" (beg. 12th c.) that the "Great Bulgaria" (Ulug-Bulgar) state was founded by Djabgusir Askypa Kuban Boyan (poet, compiler of the epos "Chulman tolgau") in 154 BC. The state included the following areas: Djalda (Crimea), Enegur (East N.Pontic from the mouth of Dnieper to the mouth of Don), Djuchi or Deremel (lands between Dnieper and Don), and Utig (Western N.Caucasus).

The capital of Ulug-Bulgar during different times were Rudjan (Great Bulgar), Bulgar-Balik, Old and New Sundugach, As-Bandja (Phanagoria). Under Sarmatian and Alanian dynasties the Great Bulgaria was disintegrating and restored until the accession of 2-nd Hun dynasty, when to power rose Djabgusir Bulümar (363-378 AD). His grandson Attila created an enormous empire from Laba to Volga - Hun-suba (432-453). The son of Attila Bel-Kermek or Irnik, in the 475 restored the "Great Bulgaria" under a name "Ak-Bulgar-Jorty" (White-Bulgar-Yurt). The Ruses and Bulgars lived there amicably, without interfering with each other. It was happening that in Bashtu (Kyiv) ruled simultaneously two rulers: a Bulgarian khan and a Rus prince. As a result of friendly interaction formed a mixed the Bulgaro-Rus ethnos under a name "Bulgaro-Uruses" of two appearances: one was of bearded Uruses, and the other of beardless Uruses, but all of them spoke Trek-Bulgarian language and responded to the name "Bulgars", which was favored by the god Tangre and his Alps. It is believed that the ancestors of that ethnic group were "Barsyls", in Russian "Borusks". Their ancestral home was the Mangyshlak peninsula of the Caspian Sea, and the Urus area in the interfluvial of Yaik and Emba. In the beginning of the new era the population moved west, to the mouth of Volga, Dnieper, Northern Caucasus. This resettlement was helped by Djabgusir Agardja Zurkap (150-189 AD), who rewarded the migrants with money and lands. The Bulgaro-Uruses developed trade, fishery, agriculture, navigation and crafts.

The Urus-Bulgars used to say: "We are Bulyars, that is Bulgars, and you are Tumars", i.e. "marsh hummocks" (Djangi Djanysh). The word "Bulyar" meant "noble Bulgar". "From that love of Urus-Bulgars to the Kara-Ulchies (Slavs, pra-Ruses), - Djangi noted (cited by Idrisi? or not cited by Idrisi, and cited from some other sourse?), - is spawned that cruelty, not explainable for many, of Urus rulers of Iskel (Kyiv Russia) to their own lay people who consist mostly of Kara-Ulchis (Slavs). And for Ak-Bulgars (Itil Bulgars)the Kara-Ulchis there were the same Bulgars as themselves". The pra-Ruses saw themselves as Slavs or Sarbians, as they were called by Bulgars. They spoke in Saklanian, i.e. pra-Slavic or Agilian language of "Prinikanie" (Perceiving), or "Veles book". But all pra-Ruses understood the Trek-Bulgarian language "Saban". After the tribes settled in the East-European plain, the northern Ruses called themselves "Bal-Rus", and the southern called themselves "Mal-Rus", later they transformed into ethnonyms Byelorussian and Malorussian. The other Bulgarian tribes influenced the Ruses: Erdims the Radimiches, Agadjirs the Drevlyans, Baylak-Bulgars the Polyans and Czechs, Sebers the Severyans, Baryndjars the Berendeys, Kibya-Bulgars the bearded and beardless Uruses. And the Rus land in Travunia, Stenia, Gardaria was called Uruskala, and it was the land of Turdjan, or Trojan, "because the blood of our ancestors irrigated it amply" (Svyatoslav the Brave) [5]. In the 7th c. the Rus was united with the Great Bulgaria restored by khan Kubrat (619 - 668). Svyatoslav of Kiev saw the Bulgar and Rus as a single state, and Ruses and Bulgars as one people, which should embark on a joint campaign in the Balkans. In his (unpublished and unexamined) "Instructions“, the Svyatoslav of Kyiv called forth: "Let us go beyond Uruskala to our Djurash (Dobrudja) steppes, and begin fighting as bahadirs for those lands of ours. We are Bulgar Uruses, that is we separated from the Slavic world (famous people?), but we still want to be famous people, and we have already shown it with our swords not a few times". And also: "About that glory Kungosh (Firebird) sings to us, continued Svyatoslav, and eagles squall everywhere, that the Uruses are free and brave on the land and in the water, in the forest and in the field". For that, from the Cimmerian times an eagle is the emblem of our state. So the most ancient geopolitics relied on the historical consciousness of the people. The loyalty to the idea - Rusian idea - Svyatoslav the Brave held to the end, with it he perished in the Dnieper cataracts (972). It was a loyalty to Atilla Audan, and Kiy Iskem. And Svyatoslav of Kyiv was their heir and successor. He recalled the words of Zabergan, or Bir-Alan (6th century AD): "Let us go south beyond Idjar (Danube), where are grazing the Bulgarian sheep of Atai (Djabgusir in the 4th century BC), and for the perfidy of our Kryashen (Greek) blood-suckers them themselves we shall cast from the Agil (Balkans) into the Ilat Sea (Mediterranean), and we shall take the whole Agil, amply irrigated with our Bulgarian blood. And if we fail to do this, our descendants will curse us, and Tangra and Nards will avert from us, and we shall hear such a roar from the heavens, and such darkness will shroud all our land that our cities and villages will flip upside down".

Patterning on Zabergan (6th century AD), Svyatoslav said this to the Rusiches (Ruses): “And we should go with his words to Djurash, only all of us shall give an oath first, that if we capture Djurash back, we shall not give it back to Kryashens, and we better all die there than with a shame return it back. If we defend Djurash and Uruskala, make them unified, rich, and mighty, our people will sing us glories for eternal centuries, and we even would receive from Tangra great favor, if our people are strong and numerous“.