What led to early villages evolving into complex societies? People specialized in tasks that helped with food production and hun
ting. When bad weather caused flooding, people could build new structures in a new location. When food was in short supply, farmers could go to special storage areas and distribute food to the most useful people. The climate and reliable water supply resulted in food surpluses that were used for growth and trade with other villages.
In conclusion many things caused tension between the US and the Soviet Union. The extreme mistrust of one another. The threat of Nuclear warfare. The soviets trying to spread communism.