Late Middle Ages: Why is this period often described as one of crisis?

Late Middle Ages:

Why is this period often described as one of crisis? You may want to treat several of the following points:

–Enviromental factors that contributed to the growing economic depression of the 14th century.

–The origins of the Black Death and responses to this pandemic.

–Revolts in Europe (Jacquerie, English Peasants, Ciompi Rebellion)

–Lollards and Hussites.

–Hundred Years War between England and France.

–How medieval Russia was different from that of Europe.