Arabic Language Spread in Khorasan (from the second century to the fifth century)

Arabic language spread in different parts ofPersiaafter Arabic-Islamic expansion in this territory. The Iranians were interested in learning Arabic, because it was the language of the Qoran and Islam and its injunctions which were based on monoism and unity of God; and equality and justice This is why one not find a book composed in scientific or historical or religious subjects or on etics during five early centuries of Islam in a language other than Arabic or beyond the Arabic impression.
This essay tries to find the ways through which Arabic language came toPersiaand the factors caused this language to remain in this aprea?