I recently got into a debate with a couple of folks over whether or not armored cavalry were a thing in the Three Kingdoms period of China. As far as I'm aware, frontal chest pieces or barding started becoming more prevalent by the late 2nd century. But heavily-armored shock cavalry were not utilized, and it would not be until the middle of the Jin dynasty in the mid-300s that heavily armored cavalry became a thing in China. One source I found that supported this was CJ Peers' "Soldiers of the Dragon: Chinese Armies 1500 BC - AD 1840", which states:
"The 4th century AD is significant in Chinese military history for the introduction of cataphract equipment for cavalry, and for the first widespread use of stirrups. Whereas in western Asia the rise of fully armoured charging cavalry long pre-dates the invention of the stirrup, in China the two innovations seem to have occurred at about the same time. What little evidence we have suggests that the latter may have been an indigenous development, while complete horse armour appears to have spread from a point of origin in the north-east. The Hsiung-nu in northwestern China first obtained panoplies in 312 by capturing them from the Hsien-pi, who had migrated from Manchuria and probably introduced the cataphract horse into China proper. The earliest depiction in art is from the tomb of Tung Shou, a Ts'in warlord buried in what is now Korea, which dates from 357. It appears that cataphract cavalry spread through China fairly quickly illustrations from the period 385—94 were found in a tomb in Yunnan in the far south-west - but the tactics best suited to their capabilities took some time to evolve."
Based on that last sentence, it would seem to me that there was a lack of even a proto-cataphract-like armored cavalry, since they didn't even have knowledge of what tactics to use for heavier cavalry.
So my question is: how heavily armored were the cavalry, and what sorts of tactics were used to employ those cavalry? If cataphract-like embodiments of heavy cavalry didn't exist, did some sort of other heavy cavalry exist?
Cavalry in China was much different than it was in Middle Ages Europe or Edo period Japan. The closes equivalent of that specific era would have been Roman cavalry. Chinese cavalry at the time used far more hardened/boiled leather with some iron coverings in their armor. Heavily armored cavalry would have been cost prohibitive for any of the three kingdoms simply because of the amount of men they would have fielded. Besides, without the modern saddle and the invention of stirrups until the 4th century a heavy laden rider would have a hard time doing much of anything besides charging in a straight line.
Chinese cavalry worked much like Roman cavalry did, where they were used to exploit flanks attacks and chase down routed units. They were not the shock cavalry that they would become. They used lances and swords by and large. I think they had a type of cavalry that used a scythcal bladed lance of some sort. China was never known for their battle cavalry at any rate.