Black Death: A devastating pandemic that swept through Europe in the 14th century, causing massive loss of life and significantly altering the demographic structure.
Urbanization: The process of population shift from rural areas to urban centers, which can impact the demographic structure by concentrating people in certain regions.
Mongol Empire: The Mongols' conquests during this period brought about significant changes in both migration patterns and cultural interchange across Eurasia, thereby influencing Europe's demographic structure.