In A Game of Thrones, one of Arya's chapters towards the end of the novel talks about how she couldn't leave King's Landing. At first, I thought this was because guards would be actively looking for her due to all the craziness happening with
King Robert's death and her father being accused of treason.
After reading on, Arya goes on to say that no one is permitted to leave King's Landing. Apparently, people are allowed in but no one is allowed out.
Why wouldn't people be allowed to leave King's Landing? In the same vein, if tensions are rising, why are people welcomed into the city to begin with?