The article is devoted to the archaeological study of the underground mosque «Kiluyet», which was founded in the XII century and continued its work until the first half of the twentieth century, occupied its place in the formation of Sufi teachings in the Islamic world and was one of the largest centers. The variety of research results, repeated changes in construction, improvements related to determining the history and activities of the underground mosque «Kiluyet», the years of construction, caused difficulties in determining the specific stage. Determining the history and timing of the construction of underground mosques allows us to accurately summarize the typological function of these structures.
Although there are many legends and stories about the underground mosque «Kiluet», scientific literature and records of travelers from all over the world, there is very little historical data, and only the results of archaeological research dating back to 1972-1973 allowed us to establish the date of construction of the ancient artifact and the condition of the original original.
The Kiluyet Underground Mosque is an underground building located 140 meters southwest of the mausoleum of Khoja Ahmed Yasawi.
The main part of the Kiluyet mosque is the underground premises of the Gar and the premises of the Mosque or Shildehana built on it. The fact that the «Kiluyet» mosques consist mainly of «Gar» and «Shildehan» rooms, we see in the construction of the «Aulie Kumshyk Ata» and «Maly Khaluat» mosques. If the «Shildehana» is partially underground, then the «Gar» must be located under its floor (Tuyakbaev, 2000:42). Ghar is a place where Sufis isolate themselves and worship. And «Shildehana» is a separate room where religious rituals are held for spiritual purification.
Archaeological investigations of the city of Turkestan, including those around the mausoleum of Khoja Ahmed Yasawi, date back only to the early years of the Soviet era, that is, the 1920s. However, there are generalizing descriptions from the writings of Russian officers and other travelers in archival materials and literature.
In the period from 1922 to 1927, several expeditions were organized and an attempt was made to explore the Turkish Republics under the leadership of the Central Administration for Archives and the Central Committee for the Environment. Archival documents show that these studies were limited to taking measures to obtain and photograph the architectural dimensions of the mausoleum of Khoja Ahmed Yasawi, repair work, and did not pay attention to the construction of underground mosques.
The archaeological expedition of D. I. Nechkin, created in 1922-1923 on special instructions from the Central Administration for Archives in the Turkish Republics, is photographing the mausoleum of Khoja Ahmed Yasawi with architectural dimensions.  For the protection and repair of the monument. The expedition included professors A. A. Semenov, A. E. Schmidt, and engineer S. K. Orlov (Mironov, 1926:28).
Even during the archaeological expedition of B. P. Denike and engineer M. M. Loginov to Semirechye and Turkestan in 1925, nothing went further than obtaining architectural measurements and photographing the mausoleum of Khoja Ahmed Yasawi (Mironov, 1926:30). The work of these archaeological expeditions is limited to carrying out architectural measurements and photographs, as well as taking measures to preserve and repair the monument. The work of these archaeological expeditions is limited to carrying out architectural measurements and photographs, as well as taking measures to preserve and repair the monument. As a result of these expeditions, in 1924, the foundation of the mausoleum of Khoja Ahmed Yasawi was investigated (Umnyakov, 1926:30).
It is partially found in the works of foreign scientists related to underground spiritual religious sites. G. Kanovets, F. Romagosa, A. Blanco, G. Priestley in their works «Orthodox Christian religious underground buildings in Greece» (Cànoves, Romagosa, Blanco, & Priestley, 2012:282-298) on the history and construction of underground religious sites during the studies of underground religious buildings and spiritual sites and M. Terzidou, S. Scarles, M. Saunders (Terzidou, Scarles, & Saunders, 2018:54-65) expresses valuable opinions in their works. From these works, it can be seen that the functions of rooms in Christian underground religious buildings were built differently than rooms in underground mosques in the Islamic Sufi tradition.
The first archaeological study of the mausoleum of Khoja Ahmed Yasawi was conducted in 1928 under the supervision of M. E. Masson. A special article and a monographic work by M. E. Masson (Masson, 1929) were published about this. However, none of these works report on archaeological investigations of the underground mosque «Kiluyet».
The analysis and examination of historical data on the underground mosque «Kiluyet» were carried out using the methods of historical-comparative and historical-typological, inductive analysis. Preference was given to comparison and analysis approaches aimed at disclosing data and the content of scientifically formulated facts related to the activities and the period of construction of the underground mosque «Kiluyet».
There is reason to believe that the first archaeological investigations of the underground mosque «Kiluyet» began in 1940 with a model designed by the architect (in the scientific literature, once a sculptor, somewhere an archaeologist, somewhere a traveler) A. L. Schmidt. This is due to the fact that the archaeological research of the underground mosque «Kiluyet» is almost entirely based on this layout. As you know, the creation of a mock-up of the capital construction of the underground mosque «Kiluyet» was not complete without archaeological research. In the work of E. Smagulov, F. Grigoriev, A. That’s what it says: «Essays on the history and archeology of medieval Turkestan» «Before the destruction of the great Kiluyet in 1940, architect A. L. Schmidt designed a model of the interior of the Kiluyet made of wood and papier-mache. It can be used to determine the appearance of the village in the first half of the twentieth century» (Smagulov, Grigoriev, Itenov, 1999:138).
The correctness of the layout is evidenced by the oral evidence of old-timers that the underground mosque «Kiluyet» operated until the 1940s, and secondly, in the book of the famous Russian orientalist V. A. Gordlevsky «Concepts of the history of the Turkestan sanctuary» it is written about Kiluyet: «Until the first half of the twentieth century, followers of the path of Khoja Ahmed Yasawi instead of worshipping him gathered in thousands (up to twenty thousand) (Smagulov, Grigoriev, Itenov, 1999:136). According to the layout, the underground mosque «Kiluyet» has an area of 20.5 x 11.5 m10 and descended from the northeast to the southwest (Senigova, 1977:47).
However, as a result of archaeological research conducted in subsequent years, the remains of the walls of the original construction of the underground mosque «Kiluyet» were discovered, which revealed the inconsistency of these walls with the layout designed by A. L. Schmidt. This is due to the fact that the construction of the underground mosque «Kiluyet» consists of several stages (Smagulov, Grigoriev, Itenov, 1999:138).

T. Shametov, researcher at the National Historical and Cultural Reserve-Museum «Aziret Sultan».
K. Baibolov, National Historical and Cultural Museum-Reserve «Aziret Sultan», Head of the Scientific Research Department.