I know little of this, but would interested to learn more.

If talking about 1800s-1900s, time frame.

I may be wrong on the details but fighters protected their ribs and solar pelx, more than the head.

Punches where thrown starting with the palm up ?, rotating if throwing a hook, so every punch thrown you could see your palm, prevent breaking your thumb on your opponent.

Punches thrown with less power, to protect hands, bc of no gloves or small gloves.
Lots of hands where broken.

Interesting fact that the spinning back fist, was banned bc it lead to so many knockouts, usually landing with the forearm instead of the knuckles.

Alot more dirty fighting was involved, thumbing to the eye, headbutts ect.