Avestan , also known historically as Zend, comprises two languages: Old Avestan (spoken in the 2nd millennium BCE) and Younger Avestan (spoken in the 1st millennium BCE). The languages are known only from their use as the language of Zoroastrian scripture (the Avesta), from which they derive their name. Both are early Iranian languages, a branch of the Indo-Iranian languages within the Indo-European family. Its immediate ancestor was the Proto-Iranian language, a sister language to the Proto-Indo-Aryan language, with both having developed from the earlier Proto-Indo-Iranian. As such, Old Avestan is quite close in grammar and lexicon to Vedic Sanskrit, the oldest preserved Indo-Aryan language.