Among the Turkish states, the first state that adopted the religion of Islam as its official religion is the state of Idyll (Volga) Bulgarians. Bulgarian Khan Almush had sent a diplomatic corps to el-Muktedir-bi'llah who was the Baghdad Abbasi caliph between the years of 920-921. He demanded from the caliph to send him Muslim jurists who would teach the religion of Islam, the masters that would construct mosques and the other fortification in his country and some money under the name of aid. The Caliph el-Muktedir accepted this demand of the Bulgarian Khan and consigned the staff and the money amount that he desired from Baghdad in June-July 921. This committee arrived to Bulgar, the capital city of the Bulgarians after a journey of seventy days. Ibn Fadlan who had participated in this committee as a clerk wrote down his memories and observations pertaining to this journey within a small book. This work was handed down until recently. According to the information provided by Ibn Fadlan, it has been understood that the Islam started to diffuse among the Bulgarians towards the end of the century IX. In the beginning of the century X, there were some small mosques built in the country of the Bulgarians and therefore, the religion of Islam was deeply rooted in the basin of Idyll. Before the arrival of the diplomatic corps to Baghdad, the Bulgarian Khan Almush must have become a Muslim in the first years of the century X. The merchants from Harezm had played a significant role in the adoption of Islam as the official religion of the Bulgarians although they were not the neighbours of the Islam State.