Why are there no Sarmatian invasions during EB's period?

[AqD]

I'm not aware of the specifics of how the Parthian was taxed, much less regarding about maintaining an army. As for farming against herding grounds, it isn't necessarily so. Normally, it isn't necessarily so. Animals can graze in areas where farming productivity could be minimal, but they could also graze in lands where there was much pasture, lands dedicated only to grazing. I suppose in the end, it would depend to each clan/noble.

Pesture lands can be changed to farms, and productivity can always be increased by various methods. In the end, lands are what we want them to be ;) Assume all lands are completely utilized, more grass lands would mean less farm lands and less food output.

Wait, you know the logistics on Nomadic army supply? I doubt that to feed entire invading army on Horseback, one would need only "a few supply".

Not much, but they certainly require less than an army of heavy cavalry formed by settled people.

Farmers weren't trained to become Horse Archers.. >_> I'd bet the noble class already practiced on Horseback Archery since children,

The cost still exists, since the nobles in sedentary society could do productive things such as governing cities or operating trades. And I doubt the cost to feed those nobles would be any cheaper than to feed professional armies of humble origins.

and if they wished for large contingents of Horse Archers, they'd have to recruit nomads to do just that. That makes much more sense in every aspect, than training settled farmers to ride and shoot like one who has been doing it for a lifetime, no?

But you'd have to pay them - mercenary HAs can never as cheap as native HAs to the nomads.