Life In Iran

According to Steven R. Ward, "Overall, the Mongol violence and depredations killed up to three-fourths of the population of the Iranian plateau, possibly 10 to 15 million people. Some historians have estimated that Iran's population did not again reach its pre-Mongol levels until the mid-20th century." In a letter to King Louis IX of France, Holaku, one of the Genghis Khan's grandsons, took sole responsibility for 200,000 deaths in his raids of Iran and the Caliphate. He was followed by yet another conqueror, Tamerlane, who established his capital in Samarkand. The waves of devastation prevented many cities such as Nishapur from reaching their pre-invasion population levels until the 20th century, eight centuries later.
In 1387, Tamerlane avenged a revolt in Isfahan by massacring 70,000 people. But both Hulagu, Tamerlane, and their successors soon came to adopt the ways and customs of that which they had conquered, choosing to surround themselves with a culture that was distinctively Persian. The mid-14th-century Black Death killed about 30% of the country's population.
Iran was gradually Islamized after the collapse of the Sassanid Empire; however, it was not Arabized. Iranian culture re-emerged with a separate and distinctive character and made an immense contribution to the Islamic civilization. When Islam came through Iran, what developed was an Iranian Islam or Persian Islam rather than the original Arab Islam, and this new Islam is sometimes referred to by scholars as Islam-i Ajam (Persian Islam).
It was this Persian Islam and Sufism which was brought to new areas and new peoples such as the Turks of Central Asia, the Ottoman Empire, and the Indian subcontinent. Among the major Iranian Muslims who cultivated Sufism and helped the spread of Islam through Sufism, one can mention Habib Ajami, Hallaj, Hasan Basri, Junayd Baghdadi, Bayazid Bastami, Maruf Karkhi, Abdul-Qadir Gilani, Moinuddin Chishti, Jalaluddin Rumi, Najmuddin Kubra, and Baha-ud-Din Naqshband Bukhari. Note should also be made of Abu Hanifa, the founder of the Hanafi school of thought which is followed by most Muslims today.