Avesta of particular manuscripts. A pre-Sasanian history of the Avesta, if it had one, is in the realm of legend and myth. The oldest surviving versions of these tales are found in the ninth to 11th century texts of Zoroastrian tradition (i.e. in the so-called "Pahlavi books"). The legends run as follows: The twenty-one "nask"s ("books") of the Avesta were created by Ahura Mazda and brought by Zoroaster to his patron Vishtaspa ("Denkard" 4A, 3A). Supposedly, Vishtaspa ("Dk" 3A) or another Kayanian, Daray ("Dk" 4B), then had two copies made, one of which was stored in the treasury, and the other
Avesta collection now lies in the Royal Library, Denmark ('K'-series). Other large Avestan language manuscript collections are those of the British Museum ('L'-series), the K. R. Cama Oriental Library in Mumbai, the Meherji Rana library in Navsari, and at various university and national libraries in Europe. In its present form, the Avesta is a compilation from various sources, and its different parts date from different periods and vary widely in character. Only texts in the Avestan language are considered part of the Avesta. According to the "Denkard", the 21 "nask"s (books) mirror the structure of the 21-word-long "Ahuna Vairya" prayer: each