i don't think the wind sock as depicted on the orlat battle plaque is comparable to the typical widnsocks with an animal-head we have seen from other people. there is evidence from other related people that windsocks or similar attachments were used.
korean (goguryeo or silla):
chinese northern dynasties (northern wei etc, a bit hard to make out on the pic):
those all seem roughly contemporary to the orlat battle plate if we assume the younger dating is correct, but the armor depicted looks almost identical to the korean armor. in case of the koreans and chinese, the windsock is being attached to the horse armor however. there is an earlier example dating from the graeco-bactrian kingdom where cavalry seems to have an attachment on the back of the rider:
Yeah, looks like standard Chinese drama stuff. Hard to tell who theyre supposed to be. The infantrymen in the background are wearing cone shaped hats that look more like Ming or Qing dynasty. Someone mightve just threw this up under Xiongnu without looking too deeply into it. Im generally suspicious of any images online that cant be traced to a source.