Under the han dynasty china blank in size and the blank road was built

Hey there!
Under the prestigious Han Dynasty of China created by the previously known peasant known as Liu Bang, China prospered in many different ways. 
When you say the size, I assume that means population and land ruled. It was one of the largest dynasties seen in China, and got a population up to 250,000 people!
During this time, people in China managed to figure out how to use the cocoons of silkworms to weave a soft and light fabric known as silk. It was highly valued all across the known world, and the empire became rich from it.
In order to keep the riches for China, anybody caught showing anybody else how to make silk could be punished, or even killed.
However, the ancient trend of empires lived on- nothing great lasted. The recipe was soon leaked, and word shot out faster than the speed of light. Soon, peole were making silk in so many different empires and dynasties, and the riches weren't only going to China anymore.
Hopefully, this helps! Be sure to come to me with any questions on this topic.