Among the following factors affecting population migration, the political factor is ① the history that the Syrian war caused many Syrians to flee their homes in 2065438+03 ②.

Political factors are generally things that the government actively implements. 1 and 3 are activities that people leave a place voluntarily to survive, and the government does not let them go. As far as the government is concerned, it has nothing to do with it, while 2 and 4 are government-led activities for some domestic economic, military and cultural needs, so 2 and 4 are the right options.