What are some theories as to how early people moved to other countries?

Question

What are some theories as to how early people moved to other countries?

 

Answer 1

Before man-made transportation (wagons and cars), humans traveled by riding on mammals.  They could have possible rode on sea mammals to get from one landmass to another landmass, if overcoming oceans.  Another possibility are bridge crossings.

 

If countries they moved to were on the same landmass, then they would ride terrestrial mammals.  Native Americans rode on mammoths.