Around 1200 BCE, another warming phase brought about social upheaval and human migration in Afro-Eurasia. The population growth and soil exhaustion in other regions forced many people to leave their homes in search of food and fertile land. Pack camels were the main source of transportation. Pack camels could carry heavy loads, and cross travel for days without drinking water, making them able to cross vast desserts. On ground pack camels were used but on water ships became more advanced. Ships had larger, better reinforced hulls, stronger masts and rigging and they had more sails. Metalworkers learned how to manipulate iron. Iron was found almost everywhere in the world and is the most used metal in world history from this time onward. Warfare
