This is part I of the Sacred Books of the East
Pahlavi Texts translation.
It includes a number of crucial medieval Zoroastrian
texts: the Bundahis, Selections of Zad-sparam, the Bahman Yast, and
the Shayast la-Shayast, as put into writing about the sixth century C.E.
The Bundahis is of note because it is a collection of Zoroastrian
traditions about the creation of the world.
The Shayast la-Shayast deals with matters of ritual impurity, sin, and rituals
related to purification, including many cases related to dead bodies.
The Bahman Yast is a prophetic text, which details thousands of
years of history, including the downfall and rebirth of the Zoroastrian faith.
West compares these texts respectively to the Biblical books of Genesis, Leviticus and Revelation.