Final answer:
The Hellenistic era saw Greek culture spread throughout conquered lands, but local cultures were allowed to persist as part of a strategy for promoting social integration and avoiding resistance, easing governance for the Hellenistic rulers.
Step-by-step explanation:
The Hellenistic era was marked by the considerable influence of Greek culture across conquered lands, partly due to the practices initiated by Alexander the Great and continued by his successors. As the Greek and Macedonian conquerors established their rule over the vast territories of the former Persian Empire, they founded new cities and replicated Greek institutions therein.
However, they allowed the conquered people to keep aspects of their own culture as a pragmatic approach to governance. This policy promoted social integration and cultural assimilation while avoiding the full-scale resistance that might have arisen if they had attempted to eradicate local customs and beliefs.
It was also in the interest of the Hellenistic rulers to maintain political stability through these cultural compromises, which helped secure the loyalty of the indigenous populations and thus facilitated smoother rule over the diverse regions within their empires.