They went deep into the remote forests to search for medicinal herbs.
Tips
usage
Evokes untouched wilderness — old growth, no roads, no phone signal. Often paired with verbs of entering/hiding (钻进/躲进/藏在). Compare with 穷乡僻壤 (poor remote area) which stresses poverty and distance from civilization rather than dense forest.
memory
Parallel structure: 深山 (deep mountains) + 老林 (old forests). 深 and 老 both signal 'untouched, primeval' — the 老 in 老林 isn't 'old = elderly' but 'old growth, ancient.'
