Najm ad-Din Kubra helped Khorezm become one of the major centres of Sufism during the 12th to the 14th centuries. Sufism is a mystical, spiritual and emotional branch of Islam, which aims for its adherents to reach God through personal meditation and secret recitation. The Sufi movement originally developed in Iraq and Syria in the early 9th century before spreading into western Central Asia. The
movement's name derives from suf, meaning wool, since the Sufis wore simple cloaks made from coarse wool. Najm ad-Din Kubra taught his pupils that they must become more Godly by personally undertaking a series of ascetic practices involving fasting, prayer and silent meditation under the supervision of a master. In time the pupil would progress from one spiritual stage to another, each symbolized by different colours; black corresponded to the lowest stage and green to the highest. Najm al-Din Kubra wrote extensively and seven of his books and 24 of his poems survive to this day. His most important book was Fawatih al-Jamal wa fawatih al-jalal, or the "Aromas of Beauty and Preambles of Majesty", where he recorded his own personal visionary experiences along with detailed guidance for students of his Sufi doctrine. In this book he described the details of the coloured lights and spots that appear when a novice undergoes spiritual training and how even the act of breathing expresses obedience to God, since the sound of exhalation and inhalation – "ha" – signifies Allah. His brand of Sufism, which became known as the Kubrawiyyah Order, was rapidly introduced to Persia, Afghanistan, India and China. At the time of Chinggis Khan's invasion of Khorezm in 1221, Najm ad-Din Kubra was already 75 years old. Legend has it that the Mongols offered him the chance to surrender before the siege of Gurganj. He refused and fought alongside his fellow Khorezmians, only to be beheaded after its conquest. His mausoleum was constructed over one hundred years later under the orders of Qutlugh Timur (a name meaning "blessed iron"), who had been appointed governor of Khorezm by Sultan Uzbeg, the ruler of the Golden Horde. Qutlugh Timur happened to be the son of Uzbeg's maternal aunt. It is not clear whether the mausoleum truly does contain the remains of Najm ad-Din Kubra. Nevertheless it still remains the most holy place in the Kunya Urgench region and attracts many local pilgrims.
