context: What is known in Iranian linguistic history as the "Middle Iranian" era is thought to begin around the 4th century BCE lasting through the 9th century. Linguistically the Middle Iranian languages are conventionally classified into two main groups, Western and Eastern.
question: మధ్య ఇరానియన్ యుగం ఎప్పుడు ముగిసింది?
answers: 9th century