"The work of Iranians can be seen in every field of cultural endeavor, including Arabic poetry, to which poets of Iranian origin composing their poems in Arabic made a very significant contribution. In a sense, Iranian Islam is a second advent of Islam itself, a new Islam sometimes referred to as Islam-i Ajam. It was this Persian Islam, rather than the original Arab Islam, that was brought to new areas and new peoples: to the Turks, first in Central Asia and then in the Middle East in the country which came to be called Turkey, and of course to India. The Ottoman Turks brought a form of Iranian civilization to the walls of Vienna. [...] By the time of the great Mongol invasions of the thirteenth century, Iranian Islam had become not only an important component; it had become a dominant element in Islam itself, and for several centuries the main centers of Islamic power and civilization were in countries that were, if not Iranian, at least marked by Iranian civilization. [...] The center of the Islamic world was under Turkish and Persian states, both shaped by Iranian culture. [...] The major centers of Islam in the late medieval and early modern periods, the centers of both political and cultural power, such as India, Central Asia, Iran, Turkey, were all part of this Iranian civilization. Although much of it spoke various forms of Turkish, as well as other local languages, their classical and cultural language was Persian. Arabic was of course the language of scripture and law, but Persian was the language of poetry and literature".