You wouldn't have. I am pretty sure it is my idea. It also requires a bit more esoteric reading than you are going to get from almost anyone else.
But basically, the eastern periphery of the Sasanian and then the Samanid states were bordered by Turkish states that had a somewhat complicated relationship with the Persians. Sometimes they were at odds, other times the Turkish groups basically served the Persians. The Samanids are the interesting ones for comparison to Amarr, because they start using some of the more persianized Turks as soldiers, governors, and generals like this guy:
http://en.wikipedia.org/wiki/Alp_Tigin Then further out to the east you have groups like the qarakhanids, which Persianize a good deal less. I would imagine the Amarr/Khanid relationship on Athra looked somewhat similar, with different groups of Khanid Amarrizing at different rates.
Of course, we don't have an Amarr equivalent of the Turkish generals taking the palace and setting up their own Persian-Turkish hybrid dynasty, so it only goes so far.