Query: How many samurai did Japan defeat the Yuan invasion with?
Context: In 1274, the Mongol-founded Yuan dynasty in China sent a force of some 40,000 men and 900 ships to invade Japan in northern Kyūshū. Japan mustered a mere 10,000 samurai to meet this threat. The invading army was harassed by major thunderstorms throughout the invasion, which aided the defenders by inflicting heavy casualties.