Tent at desert campground. As we entered the desert earlier in the day, we stopped at a police check point, had our passports held for 45 minutes, and were then told we could not sleep in the desert and would have to leave the desert by 4:30 PM. As it turned out everyone had to leave the desert by 4:30 for a possible security issue. However we did not learn that until much later and after we left the checkpoint the police followed us the entire day until we left the desert.