As the most of the great and famous Iranian poets lived from 6th to 9th century (H), this period of time is one of the most important ears of Persian literature and the most distinguished masterpieces of Persian literature, except Shahnameh, were created in this era. Changing the style of Persian poetry from Khorasani to the middle, and then to the Iraqi, is the result of some political, social and cultural factors that occurred in this historical time. The Mongol destructive invasion of Iran caused excessive massacre and plunder, devastating many of the greatest rural communities, murdering or wandering most of the scholars and scientists , and obliterating most of the scientific and literary treasures of the country. Nevertheless, and coincident with the Mongols savage rule over Iran, there were many great poets and authors who created significant and eternal works that one could not find the same or even similar literary works in other periods of Iran history; Aˈttar, Moulavi and Saˈdi are among them.