Rear view of mausoleum where banna'i technique - patterns of glazed brickwork - can be best observed.Khawaja Ahmed Yasawi

Khoja Ahmed Yasawi (Khawaja or Khwaja (Persian: خواجه pronounced khâje) corresponds to "master", whence Arabic: خواجة khawājah), also spelled as Khawajah Akhmet Yassawi, was the 12th-century head of a regional school of Sufism, a mystic movement in Islam which began in the 9th century.[1] He was born in Ispidjab (modern Sayram) in 1093, and spent most of his life in Yasi, dying there in 1166.[2] He is widely revered in Central Asia and the Turkic-speaking world for popularizing Sufism,[3] which sustained the diffusion of Islam in the area despite the contemporary onslaught of the Mongol invasion.[1] The theological school he created turned Yasi into the most important centre of learning in the region. [4] He was also an outstanding poet, philosopher and statesman.[4] Yasawi was interred in a small mausoleum, which became a pilgrimage site for Muslims.[5][4]

New mausoleum  A view of the mausoleum, ca. 1879.

The town of Yasi was largely spared during the Mongol invasion of Khwarezmia in the 13th century.[6] Overtime, the descendants of the Mongols settled in the area and converted to Islam.[5] The town then came under the control of the Timurid dynasty in the 1360s.[1] Timur (Tamerlane), the founder of the dynasty, expanded the empire's realm to include Mesopotamia, Iran, and all of Transoxiana, with its capital located in Samarkand.[1] To gain the support of local citizens, Timur adopted the policy of constructing monumental public and cult buildings.[6] In Yasi, he put his attention to the construction of a larger mausoleum to house Yasawi's remains,[7][8] with the intention of glorifying Islam, promoting its further dissemination, and improving the governance of the immediate areas.[8]

The new mausoleum was begun in 1389.[1] Timur imported builders from cities which he laid waste during his campaigns, including mosaic-workers from Shiraz and stonemasons and stucco-workers from Isfahan.[5] The master builders were led by Khwaja Hosein Shirazi from Iran.[9] Tradition holds that Timur himself participated in the design of the structure,[5][8] where he introduced experimental spatial arrangements, types of vaults and domes. These innovations were later implemented in the religious edifices of other cities.[1] However, the mausoleum was left unfinished, when Timur died in 1405.[1]

 The dome of Khoja Ahmed Yasawi's mausoleum is the largest in Central Asia.Decline and preservation

When the Timurid Empire disintegrated, control of the immediate territory passed on to the Kazakh Khanate, which made Yasi, then renamed Turkestan, its capital in the 16th century.[10][11] The khans (Turkic for "ruler") sought to strengthen the political and religious importance of Turkestan to unify the nomadic tribes within the young state.[11] Hence, as the khanate's political center, ceremonies for the elevation of the khans to the throne and missions from neighboring states were received in Turkestan.[10] The Kazakh nobility also held their most important meetings to decide state-related matters in the capital.[11]

 Plan of Mausoleum.

The town, situated on the border of the nomadic and settled cultures,[10] flourished as the khanate's largest trade and craft center.[11] Fortifications were erected to safeguard this commercial role,[10] including the 19th-century construction of defensive walls around the unfinished mausoleum,[1] which became an important landmark and pilgrimage center of the town. In the succeeding centuries, Turkestan and its historic monuments became connected with the idea of the Kazakh state system.[11][12] Political struggles and the shift in overland trade in favor of maritime routes soon led to the town's decline, before it finally passed on to the Russian Empire in 1864.[1]

 General View of Sultan Akhmed Yassavi's Mausoleum from the Southern Side (historic photo, created on around 1865-1872)

The town was eventually deserted; a new town center was developed west of the area, built around a new railway station.[1] The territory came under Soviet rule by the 20th century. The new administration carried out preservation and restoration work on site,[1] although they considered it more as an architectural rather than a spiritual structure. Hence, the mausoleum was closed to the devotees who came to pay homage to Yasawi.[5] Nevertheless, the local khoja based at the mausoleum allowed pilgrims to secretly enter the structure at night.[13] Beginning in 1922, several commissions took part in the technical investigation of the building.[8] Regular maintenance has been in place beginning in 1938, while a series of restoration campaigns were started in 1945, with the last one being held from 1993 to 2000.[1] Among the latest conservation steps implemented were the replacement of the structure's clay foundation with reinforced concrete, the consolidation of walls, the waterproofing of the roofs, and the layering of new tiles, based on historic designs and patterns, on the domes.[1] The continuous conservation works have been in place when Kazakhstan gained its independence. The building is protected as a national monument and is included on the List of National Properties of Kazakhstan. The site is under the administration of the Azret-Sultan State Historical and Cultural Reserve Museum, in charge with the safeguarding, research, conservation, monitoring and maintenance of the mausoleum.[1]