The Chinese nation provides an extra citizen defenders. Specifically, the Chinese increases the number of Citizens by 1 and also grants bonus defenders at the Town Center by 1 at every age.
The Chinese nation is a good choice if you wish to focus on building and strengthening the Economy as an additional citizen is surely helpful to get along tasks in the city. This focus on economy is also complemented with the presence of extra defenders during an attack.
The unique unit that the Chinese nation produces is the Chu Ko Nu, which are great agains enemy troops and which also produces a faster rate of fire. This unit also produces a high damage multiplier of 400%.