Not sure what you mean by "dispersing"? Do you mean citizens just leaving their cities?

As far as control, Warlords or Emperors would appoint Prefects of cities, who were responsible for the upkeep and improvement of the cities. These Prefects were generally trusted, proven and able generals or advisers. They took care of everyday government matters and often had a few advisers (sometimes hundreds depending on the city) that helped them with economic and civil matters. They also were granted a few generals in case an army was needed to quell an uprising or take care of crime in town. Cities also generally had 4 main gates (North, West, East, South), they were always stationed with guards and if you wanted to enter you either needed to be a merchant or have a pass from another Prefect, Warlord, etc.

I'm honestly not sure if peasants were ever allowed outside the cities unless they were displaced because of an attack, storm or other disaster that fell upon the city. More than likely, peasants didn't have the resources to travel anyway because if you were a farmer, you were basically the equivalent of a serf.

When news broke, Prefects, Emperors or Warlords sent out a messenger with the news who would travel on horseback day and night till he arrived, often first to the city with which the news is most important to (ie, learning of a secret attack toward a certain city). The other way news spread, is between travelers, troops and merchants who would spread the news or rumors into the cities.

Edit: Added a bit more detail/grammar