"[This region is subject to] “a process of spiritualization of Avestan geography … in the famous celebration of the Hilmand in the Zamyad Yast…”, and “this pre-eminent position of Sistan in Iranian religious history and especially in the Zoroastrian tradition is a very archaic one that most likely marks the first stages of the new religion … the sacredness of the Hamun-i Hilmand goes back to pre-Zoroastrian times…” ..."