[corsac]

And if A and B voluntarily engage in mutually beneficial trade, and C who rules over B (and holds trade and aliens both in contempt for ideological reasons) obstructs B and A from trading in order to weaken A, what is that?

[lmm]

Well, is C's rulership over B legitimate or not? We generally recognise that legitimate governments have the authority to block their subjects from trading, even today (e.g. try buying something from Cuba).

[corsac]

Were anything like modern notions of political legitimacy and just war current across Silk Road era Eurasia, or not? And didn't you just say it was a Hobbesian war of all against all anyway?

More to the point, supposing C has a robust pattern of responding to a trade overtures from nomadic A by violence towards A's representatives, and of justifying the response using an intransigently chauvinist characterization of A (the ahistorical "good peasants vs. bad nomads" construct alive and well in certain comments in this thread) – without imposing anachronistic comparisons or standards, is there a better way to understand A's retaliation than essentializing them as "parasites"?