In politics, the hegemon is the leading power in a region. For example, in the 6th century BC, Sparta became the hegemon of the Peloponnesian League. In modern times, the Cold War (1945 - 1990) was a battle for hegemony between the communist east led by the USSR and the capitalist west led by the US. Both sides were superpowers battling to dominate the arms race and become the supreme world superpower.