Exactly. The explanation seems to invoke Zoroastrianism, but not in any sensible way. You might assume that pale yellow refers to Zoroastrians, but that seems

Exactly. The explanation seems to invoke Zoroastrianism, but not in any sensible way. You might assume that pale yellow refers to Zoroastrians, but that seems unlikely, given its predominance in counties throughout the country and lack of registering at all on the state map. It looks like a pattern more similar to "No Presence," which I take to mean there simply aren't any discoverable congregants other than Christians in certain vast stretches of the, uh, Northern Rocky Heartland (for lack of a good regional descriptor).