Hi, there! :)
During the Pleistocene Ice Age, the climate belts of the northern hemisphere shifted to the south due to changes in:
- ocean currents,
- atmospheric circulation patterns,
- and Earth's position in relation to the sun.
This caused formerly temperate regions to be covered in ice, while areas that are now tropical experienced cooler and drier conditions. This shift had significant impacts on the distribution of flora and fauna, as well as on human societies.
Hope that helps! Good luck! ^_^