The document discusses the fall of the Yuan dynasty in the 14th century due to internal disintegration and external challenges, as well as natural disasters. It then describes how Zhu Yuanzhang, an unlikely candidate, went on to found the Ming dynasty after defeating other rebel groups, unifying China and establishing new political institutions. Finally, it outlines how Zhu Yuanzhang's son, Yongle, usurped power after a succession crisis and went on to reform the government and make Beijing the new capital city while defending China's borders.