Periods of famine, warfare, and religious persecution have most often influenced people’s decisions to

Migrate from one region to another

Explanation:

Famine -food scarcity-, warfare -war situations-, and religious persecution have most often influenced people’s decisions to migrate from one region to another.

For centuries, people have migrated from one region to another to escape from tough situations like food scarcity, war, racism, lack of opportunities, religious persecution, amongst many others.

Migration can permit an individual or group of individuals (family) to have access to better opportunities and live a better-quality life.

rain should be the answer.