What historical evidence is there that disease killed the bison herds en mass?

Why aren't all the bison herds in America gone today?

Why did every single bison every where get killed except a couple very remote herds in the north. All herds in the east and south were killed.

Why were the killing fields in the same location hunters were and not off in the wilderness?

Why didn't Indians see remote bison herds dieing en mass far from the whites in the north short grass prairies?

To be honest I don't care what people believe about the bison. It matters not. I want to believe truth and the best evidence supports human rifles as the ultimate demise of the herds. Human rifles slaughtered all the cervid herds out west too.

I'm not antihunting. I love and support hunting. I'm just not going to lie to myself.