Literature in Iran
Persian is Iran's official language and the language of the country's ethnic majority (i.e., the Persians), and Persian literature has been the country's most influential literary tradition. Apart from Iran, Persian literature was used and developed further through several medieval Persianate societies in Asia Minor, Central Asia, and South Asia, and the language is still used widely in Central Asia (Tajikistan and Uzbekistan) and Afghanistan.
Eastern Iranian languages
The Eastern Iranian languages are a subgroup of the Iranian languages emerging in Middle Iranian times (from c. the 4th century BC). The Avestan language is often classified as early Eastern Iranian. The largest living Eastern Iranian language is Pashto, with some 50–60 million speakers between the Hindu Kush mountains in Afghanistan and the Indus River in Pakistan. As opposed to the Middle Western Iranian dialects, the Middle Eastern Iranian preserves word-final syllables.