[Cronos]

Just as an aside, the primary reason for the collapse of the religion was a 20-year long religious war between Zoarastrian Persia and Christian Byzantium.

Actually it wasn't 20 years, more like an ongoing war right from the time of Emperor Trajan in 130 AD until the 600s

[Mark Noonan]

True, in the longer scheme...but that 20 years war right at the end was pretty big...