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.