During the rule of the Han emperors, China enjoyed a 400 year period of peace and prosperity. This period of time is known as Pax Sinica, which means "Chinese Peace." During this time, the Han emperors established a strong central government that was designed to help the people and protect them.
One such innovation was the storage of food. During times of plenty, Han emperors would have great amounts of food put up into storage. Then during difficult times, they would sell these food stores, helping to stabilize food prices.
The Han also abolished the practice of giving powerful government positions to members of the royal family. They wanted the most capable leaders to control government. To insure that the most talented leaders were given government posts, the Han Emperor Wudi instituted a series of written exams. Anyone could take the tests. Those who received the highest scores were given posts in the government.