The sects have never escaped the attention of the political institution. This link between politics, the state, and the sects deserves attention to its causes and consequences. In this context, it is important to evaluate the sect politics established by the Great Seljuk State, one of the four great states established by the Turks in history, in terms of Islamic civilization and philosophy. Because the frame of the sect shaped by the Seljuk period was maintained for a long time. The foundation period of the state included in the mission time of the first Sultan Tughrul Beg. Establishment of the Seljuks contains a story about the domination of historical, geopolitical and geostrategic geography. Different religions, traditions and sects were in the geography of Seljuk. When the fıqhi schools of Khorassan and Mavera were examined, two sects came to the fore: Hanafisim and Shafiism. Hanafism was very active in this region. As a matter of fact, Selcuk Beg preferred Hanafism as a sect. Hence, the Seljuk dynasty was generally a member of the Hanafism sect. As it is known, the main expansion center of the Shafiism was Egypt. However, Shafiism succeeded to open up the geography of Khorasan, winning new impetus with the educational activities of Abu Ishaq Mouvez (340/951). In the time of Tughrul Beg, Shafiism had a large number of fans in the towns of Khorassan. There had an ongoing struggle between Hanafis and Shafiis in in the geography of Seljuk. Different sects created the block next to these two sects. Therefore, this ancient struggle experienced over the Mutazilites and Asharis in the period of Tughrul Beg. Tughrul Beg appointed Amidulmulk Kunduri, the Mutazilite, as a vizier. Tughrul Beg and Vizier Kunduri were the determinant in sectarian politics in the foundation period of the state. The main objective of sectarian politics carried out by Kunduri was to support the Mutazila-Hanafi people. In this context, the qadi, the preacher and other bureaucratic duties were given to the Mutazila-Hanafi masses. Thus, Mutazila-Hanafi persons were brought to important tasks. Pressure and intimidation policies were applied against Rafidite, Ashari-Shafii-Sufi groups in this period. These politics which carried out under the leadership of Vizier Kunduri were called the Seljuk Mihna. According to sources, the Seljuk Mihna took place between 445/1053 and 455/1063 and lasted for ten years. The Seljuk Mihna began with the coming of Vizier Kunduri and continued until the death of Tughrul Beg. The first step towards the Asharis in Mihna politics was realized by cursing the Imam Ashari and Asharite from pulpit. There were pressures and inquiries against Asharis in the process of Mihna. Abu Abdullah al-Hubbazi (447/1055), one of the famous people of the time, was questioned. Juwayni, one of the eminent scholars of the Ashari-Shafii identity, was a struggle with the Mutazilites and entered into controversy with them. Therefore he was the target names in this process. One of the names that were investigated in the Seljuk Mihna was Furati who was Ashari-Shafii scholars. Among those who were subjected to pressure and intimidation policies were persons with Sufi identity. Al-Qushayri (465/1072) was one of the famous Sufis of this period and was placed on the target board. The Mihna practices were carried out with the support of the bureaucrats, such as the judges and the orators, whom Kunduri appointed. What are the main reasons for the Seljuk Mihna? There is a need for a holistic view as a method. It seems difficult to analyze the issues before considering the political, social, economic, cultural and sectarian structure of the preSeljuk region. There are sectarian conflicts that political disintegration reveals, as well as alliances between sects on the other side. After this general acceptance, practices of Seljuk Mihna become clearer. The struggles in the Seljuk Mihna are based on the dispute between the Hanafi and Shafii schools in terms of their historical roots. Two main parties have formed in the struggle between the Hanafis and the Shafiis. Other sects also took positions according to Hanafi and Shafiis. The sectarian politics of foundation period of state enlarged the field of the Mutazila and Hanafi schools. On the other hand these politics seriously hurted Shafiism and Asharite, the shining star of the period, and other social belonging to which it was related. In this context the sectarian-political relation of the foundation period also influenced the later periods of the Seljuks. After Alp Arslan came out on the throne, the whole sect politics shifted. In the new period, Vizier Nizamulmulk was a serious influence. Keywords: Seljuks, Tughrul Beg, Secterian Movements, Mutazila, Asharite.