How did the roman empire support its expansion and integrate culture on three continents?

Answer 1

First of all it has to be noted the the Roman Empire did not cover the whole of three continents. It included only part of them. In Europe it covered the west up to the the rivers Rhine and Danube and the Balkan Peninsula in the southeast. In Africa it covers only the Mediterranean coast. In Asia it included only Turkey Cyprus, Syria, Lebanon and Israel/Palestine. The Eastern Mediterranean (Greece, the territories in Asia and Egypt) had already been unified culturally by the Greeks before the Roman conquests). Africa west of Egypt was Berber. The greatest cultural diversity was in Europe.

The Romans maintained the stability and strength of their empire by respecting the peoples they conquered. They respected their religions and customs and allowed them to continue to worship them. They also allowed them to continue to use their customary laws at the local level, which they called mos regionis (regional traditions/laws of the land). They relied on the local ruling elites to run local affairs in the provinces. This policy fostered political and social stability. It had two advantages: it facilitated the integration of the locals in the provinces (the conquered peoples) into the ideology and the economy of the empire and it reduced the administrative load (and the associated costs) of the provincial governors. It limited the job of the governors to defence and the maintenance of the legions stationed in the provinces, the commissioning of public works and arbitration of disputes the locals were unable to settle themselves. A less tolerant policy would have led to rebellions and would have threatened the stability of the empire. The conquered peoples also benefited form their participation in the thriving trading networks of the empire, which favoured both economic and cultural integration. In addition to all this, the Romans fostered the worship of the cult of the emperor and an imperial ideology to help with cultural unification.