The presence of Arabs in Iran and continuation of this presence for almost 3 centuries in this country has had fundamental effects on Iranian language and literature. Most of researchers have analyzed this fact form the negative view point. In this study we try, by making use of sufficient reasons and from a positive point of view, to show that despite lack of Iranian literature in this era (early Hijri centuries), it can't be construed that we had absolute silence of Iranian literature, yet Iranian language and literature in a dynamic and complex way passed a progressive period in a way that it paved the way for growth of Iranian poetry and literature in the following centuries. Although Iran lost its Pahlavi writing system in this era but with passing of time and along with capabilities of Iranians, Farsi language was born and with widespread use of  Arabic writing system  as an effective and simple  instrument (in comparison with other writing systems)  which thanks to  acceptance of Islam  and wide spread use nationwide , Farsi language  became Iranian national language with the support of independent  rulers. In fact in this era the relation of Iran and Arabs by passing many ups and downs in a bilateral benefit, in one hand caused the unity of language among Iranians and their use of a modern language and its spread and in the other hand, with presence of Iranian elites in expansion of Arabian poetry, valuable services has been paid to Arabic language and Arabic language has passed a progressive era.