Since broth is mostly
water, as you say it would take a long time to evaporate all that away, even if you put as little water in as possible. Vegetables and dried meat are both much more easy - I can imagine putting a broth mix together with those. I'd be inclined to buy a goof quality stock cube as Anne has suggested. However I did find a useful
video on
this thread about dried stew mixes, suggesting using a slow cooker to give a dehydrated broth base: