You wrote:
“No doubt Mongol Buddhists deep into Zen roamed the streets of the burned out city of Baghdad searching for Red Bearded Persians...”
Persians in Iraq rather than Iran being sought out by Zen Buddhist Mongols who were actually Mahayana Buddhists?
” today’s Persians no longer have red beards so the search would be unfruitful.”
Red hair is still seen in Iran even today: http://www.raceandhistory.com/cgi-bin/forum/webbbs_config.pl/noframes/read/1524
Now, regarding Buddhism among the Mongols, Zen had already reached Persia ~ as it had reached every part of the Mongol Empire. Given the way Buddhism is structured, focusing on a stretch of verses in a single Sutra is not really seen as being different from the folks who focus on a totally different stretch of verses in a different Sutra.
Think of it as a "Big Tent, Party On Dudes".