I'm not sure how early you're thinking, but the late mediaeval ages did have ways of preserving the body, and it's perhaps not a coincidence that this is the time when autopsies begin to be performed. Basalm, myrrh and other preservatives were the first stage, evisceration of the organs the next, and then finally some sweet-smelling spice/herb mix to mask the putrefaction process - quite how long that takes I'm not sure, but there probably was a reason that autopsy theatres were large to allow air circulation.