When did Persian become an important literary language?

Persian emerged as an important literary language during the 9th and 10th centuries, a period often referred to as the Iranian renaissance. Following three centuries of Arabic hegemony, this "New Persian" developed as a written language in the eastern Iranian lands, particularly under the patronage of the Samanid dynasty in Bukhara.12

The language was cultivated through the adaptation of scholarly works and the establishment of a courtly tradition of poetry. By the 10th century, poets such as Rudaki had crystallized the imagery and formal characteristics of Persian lyrical poetry. This literary momentum culminated in the composition of the Shāh-nāmeh ("Book of Kings") by Ferdowsi, which was completed in the early 11th century and served as a definitive expression of Iranian national identity and history.123