The Zend Avesta is a Persian/Iranian text of Zoroastrianism. This book speaks about the lands and gods of the people speaking the Indo-Iranian languages.  

• It has references to the regions of northern and north-western parts of India. It has terms which show linguistic similarity with the Vedas.  
• This text is indirect evidence that the early home of the Aryans was outside the Indian subcontinent. 

Source: Tamil Nadu state board.