Some cars and many tents are set up at the foot of a mountain.
No one was able to drive to the camp site.
Many tents cannot be set up if no one could drive to the foot of a mountain.
There cannot be no one if there are some cars.
there is information about the setup of cars and tents in sentence 1 but, in sentence 2 it is mentioned that  No one was able to drive to the camp site.