How was rome able to keep control over such a large empire?

Answer 1

Rome kept such a large empire unified through tolerance, legal protections, proving benefits, Propaganda and the army.

The Romans tolerated the religions and customs of the conquered peoples. They allowed them to continue to worship their religions, follow their customs and use their customary laws at the local level. They also let the local ruling classes run most of the local affairs. The role of the provincial governors of the provinces (conquered territories) was restricted to defence and maintenance of the legions stationed in the provinces, tax collection, public works and the arbitration of disputes the locals could not resolve by themselves. This policy had two advantages: it reduced the administrative load of the provincial governors and it facilitated the integration of the locals into the ideology and the economy of the empire. A less tolerant policy would have led to too many rebellions and would have threatened the stability of the empire.

In 225 BC the emperor Caracalla extended full Roman citizenship to all the freeborn in the Roman Empire Prior to this, the provincials, the people outside Italy who had been conquered or were under Roman influence, enjoyed the rights of jus gentium (the law of nations). Nation in the Latin was the word for ethnicity and just gentium was a sort of natural law which was regarded as "innate in every human being." The rights it conferred were considered to be held by all persons. They were based on the notion that the concept of justice sprung from the natural reason of the human mind rather than ethnicity and that they applied regardless of citizenship. Through this, the provincials enjoyed the protection of Roman civil law in their dealings with Roman citizens. Cases between Romans and non-Romans were adjudicated by the praetor peregrino, the chief justice for foreigners, who was supposed base his rulings on fairness and on Roman civil law. .

Being part of the empire also provided economic benefits and, sometimes, security. The empire developed thriving trading networks and the Romans encouraged the peoples in the provinces to increase the production of manufactures agricultural goods for trade. The wealthy and middling class benefitted from this. The exploited poor did not. The Roman legions stationed in the provinces helped with maintaining order. In the frontier areas they also provided protection from raids from across the border. The troops were also customers for local traders.

Answer 2

because Rome had many victories and it started to expand so much

and after that they had to cut in half