Some cars and many tents are set up at the foot of a mountain.
Cars and tents are at the foot of the mountain.
Cars and tents set up at the foot of a mountain are definitely are at the foot of the mountain.
some cars and many tents means there are cars and tents
Cars and tents are at the foot of the mountain because some cars means more than one car and many tents implies more than one as well. If they are set up there then they are at the location.