Avesta people. The term "Avesta" is from the 9th/10th-century works of Zoroastrian tradition in which the word appears as Zoroastrian Middle Persian "abestāg", Book Pahlavi "ʾp(y)stʾkʼ". In that context, "abestāg" texts are portrayed as received knowledge, and are distinguished from the exegetical commentaries (the "zand") thereof. The literal meaning of the word "abestāg" is uncertain; it is generally acknowledged to be a learned borrowing from Avestan, but none of the suggested etymologies have been universally accepted. The widely repeated derivation from *"upa-stavaka" is from Christian Bartholomae ("Altiranisches Wörterbuch", 1904), who interpreted "abestāg" as a contraction of a hypothetical reconstructed Old Iranian
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