Demographic Crises
Population in 1300
Although our sources are scattered and uneven, we do know some things. We know that the population of Europe began a period of strong growth around 1050 and that this expansion lasted up to around 1300 or a little beyond. Why it grew is much discussed and isn't germane here. But there's little doubt that something changed in the first decades of the 14th century. The reasons for the change are also much discussed and I don't regard the matter as resolved yet, so don't take what follows here as an "answer".
Climate seems to have had something to do with it. The earlier centuries saw a period of warmer, milder weather, whereas the period from roughly 1300 to 1450 saw cooler, harsher weather. The correspondence isn't close enough to claim cause and effect, but certainly climate was one contributing factor.
It seems likely that Europeans were running out of the best land, that new lands brought under cultivation in the late 1200s and early 1300s were marginal, giving lower yield per acre and requiring more work to maintain. And more at risk if other things (like weather) went bad. Perhaps endemic warfare had an effect, not so much in actual battlefield deaths as in effects on farmlands and livestock.
Whatever the reasons, the population of Europe in 1300 was showing signs of stress. The strong eastward expansion known to the Germans as the Drang nach Osten (drive to the east) had slowed in the later 13th century. The Crusader states had fallen in 1291. By the 1320s, the Ottomans were beginning to drive back the Byzantines. Even so, the cities of Europe were continuing their boom times, the Dutch were still reclaiming polder lands, and trade was prospering.