Body / Mind – why are they different?

In Buddhism it's mostly all about mind training. The mind is regarded as a skhanda/aggregate separate from the body. Also, feelings, consciousness and karmic conditions. Now I am in doubt, thinking that the body could produce the mind. If so, that would mean, that the Buddhist path is stripped of many implications, like that we are wandering in samsara since beginningless time. Could someone please provide some links or explanations which explain the Buddhist argumentation that body and mind are separate "entities"/ aggregates. Thank you.