Avestan , formerly also known as "Zend", is an Iranian language of the Eastern Iranian division, known only from its use as the language of Zoroastrian scripture, i.e. the Avesta, from which it derives its name. Its area of composition comprised ancient Arachosia, Aria, Bactria, and Margiana, corresponding to the entirety of present-day Afghanistan, and parts of Pakistan, Tajikistan, Turkmenistan, and Uzbekistan. The Yaz culture of Bactria-Margiana has been regarded as a likely archaeological reflection of the early Eastern Iranian culture described in the Avesta.