Coins of Turkic Bolgars IX-Xth with Turkic script on it.
Idil Bulgar Mosque and the Russian Church
Some Notes about Volga Bolgars:
Since the middle of the VIIIth century the Turkic-speaking Bolgar tribes penetrated into the Middle Volga region. The most well-known among them are the Barandgars, the Bolgars, the Bersula, the Suvar and others, who came from the regions of the north-western pre-Caucasus as a result of the Arabian-Khazar wars of the 732-735.
Nearer to the Xth century came the second wave of the Bolgar migration to the Middle Volga and the Kama region from the southern steppes. At the same time constant immigration of the Ural-Kama and South Ural population, including the Ugrian (Madjar) tribes, was taking place.
In VIIIth - Xth centuries the basis of the culture of the new people - the Volga Bulgarians - is being laid as a result of the interaction of the Turkic-speaking Bolgar tribes and the Finno-Ugrian population. In the Xth century the early-feudal state of the Volga Bulgaria has been formed in the Middle Volga region. During the period of its formation Bulgaria was in the state of vassalage with the Khazar khanate and occupied a small territory in the region of Kama and Volga confluence. It was as early as that time that several towns - tribal centres - existed. They are Suvar, Bolgar on Volga, Bolgar-Bilyar, Oshel', etc.
One of the main supports of the state was the Moslem religion, officially accepted by the Bulgars in the beginning of the Xth century. The flourish of the Volga Bulgaria corresponds to the XIth - beginning of the XIII century. The basic territory of the state significantly grew.
The archaeologists nowadays recognise more than 1500 Bulgarian sites of the pre-Mongolian time on the territory of Bulgaria. The foundation of economy of the Volga Bulgaria was the highly developed plough agriculture and animal husbandry. Crafts were of great significance - metallurgy, blacksmith's, jewellery, building, pottery-making, glass-making, bone-cutting, tannery, weaver's crafts and others. The third important component of the Bulgarian economy was trade.
The flourish of the Bulgarian trade was much due to the location of the state on the most important intercontinental trade route - the Volga-Baltic route as well as to the high level of the craft and farming development.
In 1223-1240 Bulgaria recklessly resisted to the Mongol hordes which strove to conquer the state. The unequal struggle resulted in the conquest of Bulgaria, the havoc of its economy and culture, the destruction of the cities. The devastated Volga Bulgaria was included into the Golden Horde.
In the Museum funds the culture of the pre-Mongolian Bulgaria is represented by numerous materials. The basic collections are АКУ-2, АКУ-85, АКУ-87, АКУ-94 - "Bolgar, Bilyar and other sites" - the united collection, the basis of which is constituted by the materials of the Society for Archaeology, History and Ethnography of the Emperor's Kazan University; АКУ-278, АКУ-279 - the sites of the Low Kama region (excavations and explorings by E.A.Begovatov, K.A.Rudenko in 1991-1997); АКУ-262, АКУ-285 - "The Bilyar site of ancient city, the inner town, the potter's workshop, the alchemist's workshop" - research by S.I.Valiulina.
"The Bolgars originally moved to the Middle Volga region in the second half of the 8th century. They arrived here from the Lower Don and the northwestern Caucasus, where in their early history they also had links with the Huns. One branch of the Bulgars moved westward from the Caucasus to the Danube, where they formed the ruling elite of the first Bulgarian state founded in 681."
"-The Turkic Bulgars who did not move into the Danube valley, who held to the wild eastern steppes, eventually were pushed by Khazar expansion northward up the Volga valley in the lands around the city Kazan where they formed a significant Islamic or Muslim Bolgar khanate."
Here's another blurb:
The Bulgar kingdom
In 921, the Bulgar king, Almas, received an embassy sent by Caliph al-Muqtadir and converted to Islam on May 12, 922. His example was followed rapidly by the ruling elite of the kingdom. At the end of the tenth century, most of the Bulgars were already Muslim, and there were mosques and schools in virtually every village. For three hundred years, the Middle Volga area remained a Muslim island—the northernmost vanguard of the dār al-Islām—completely surrounded by Christian or animist neighbors. Its ties with the faraway Muslim world were maintained through the Volga trade route.
In spite of, or perhaps because of, their isolation, the Bulgars were zealous Muslims from the beginning. They played a role in the conversion of some nomadic Turkic tribes, the Pechenegs and Cumans, to Islam. They also nursed hopes of spreading Islam to the Russians, who were at that time still animists. In 986 a Bulgar embassy was sent to Kiev with the aim of converting the grand prince, Vladimir. The Russian Primary Chronicle recounts that some time later, Vladimir, in search of a suitable religion, also received representatives of Western and Eastern Christianity and of Judaism and heard each speak in turn of the merits and tenets of his faith.
Little more is known about the cultural history of the Bulgar kingdom prior to the thirteenth century. One may assume that Islam remained the religion of the Turkic city-dwellers, the feudal elite, and the merchant class, while the rural population, of whom the majority was ethnically Finnic, remained animist.
Here's from another unknown source
BOLGARI, or BOLGARY
A ruined town of Russia, in the government of Kazan, 4 M. from the left bank of the Volga (known to the Tatars as Etil, Jill or Atel; to the Finnish tribes as Rau, and to the ancients as Rha and Oarus)
at 550 N. lat . It is generally considered to have been the capital of the Bulgarians when they were established in that part of Europe (5th to 15th century) . Ruins of the old walls and towers still survive, as well as numerous kurgans or burial-mounds, with inscriptions, some in Arabic (1222-1341), others in Armenian (years 557, 984 and 986), and yet others in Turkic. Upon being opened these tombs were found to contain weapons, implements, utensils, and silver and copper coins, bearing inscriptions,in ordinary Arabic, others in Kufic These and other antiquities collected here are preserved in museums at Kazan, Moscow and St Petersburg . The ruins, which were practically discovered in the reign of Peter the Great, were visited and described by Pallas, Humboldt and others . The city of Bolgary, Bolgari was destroyed by the Mongols in 1238, and again by Tamerlane early in the following century, after which it served as the capital of the Khansof the Golden Horde of Mongols, and finally, in the second half of the 15th century it became a part of the principality of Kazan, and so eventually of Russia
The Arab geographer Ibn Haukal states that in his time, near the end of the 10th century, it was a place of 10,000 inhabitants .