Why did the incans build such a large road network in their empire?

The extensive reach of the road network allowed the incas to better move armies across their territories in order to further expand the empire or maintain order within it. trade goods and tribute from conquered peoples - both goods and people - could also be easily transported to and from the major inca centers, typically using llama caravans and porters (there were no wheeled vehicles). inca administrative officials also traveled  along the roads in order to dispense justice or maintain records such as local agricultural production, tribute quotas, and censuses.