Answer: Rome united its empire by the spread of Roman law, as well as a network of roads that helped soldiers move and keep order.
Step-by-step explanation:
The Roman Empire was established in 27 BCE following the demise of the Roman Republic, following a period of civil wars.
The Roman law was a complex body of precedents and comments. The network of roads was without a match at the time, planned for relatively quick transportation and propper for many diverse functions such as commerce, mail delivery, agriculture, and military actions.