Complex sentence: Most settlements of the Caucasian Mountains' valleys were built where it was most convenient on the valley floor, however, all the old auls of the Karmadon Valley were built on the valley slopes and even on the crests of the nearby ridges.
Split into simpler sentences: Most settlements of the Caucasian Mountains' valleys are built where it is most convenient-on the valley floor. However, all the old auls of the Karmadon Valley were built on the valley slopes and even on the crests of the nearby ridges.