Greek history and culture was significantly shaped by conflicts with the Persian Empire in the 5th century BC. The Greeks were able to defeat the Persian invasions thanks to the military prowess of the Spartans on land and the Athenians at sea. This allowed Greek civilization, including democracy, to flourish. Later, Alexander the Great expanded Greek influence throughout Asia and North Africa through his military conquests. Ancient Greek achievements in many fields including architecture, art, philosophy, science, and mathematics had enduring impacts and influenced Western civilization.