The document discusses several major turning points in medieval Europe during the High Middle Ages: the Crusades, which ended Western European isolation and led to increased trade; the Magna Carta signed by King John, which established early limitations on royal power; the Hundred Years' War between England and France, which strengthened both monarchies; the Babylonian Captivity and Great Schism, which weakened the Catholic Church's authority; and the Black Death plague, which killed a third of Europe's population and accelerated the decline of feudalism.