<P> For 18th - century historians studying the 14th and 15th centuries, the central theme was the Renaissance, with its rediscovery of ancient learning and the emergence of an individual spirit . The heart of this rediscovery lies in Italy, where, in the words of Jacob Burckhardt: "Man became a spiritual individual and recognized himself as such". This proposition was later challenged, and it was argued that the 12th century was a period of greater cultural achievement . </P> <P> As economic and demographic methods were applied to the study of history, the trend was increasingly to see the late Middle Ages as a period of recession and crisis . Belgian historian Henri Pirenne continued the subdivision of Early, High, and Late Middle Ages in the years around World War I . Yet it was his Dutch colleague, Johan Huizinga, who was primarily responsible for popularising the pessimistic view of the Late Middle Ages, with his book The Autumn of the Middle Ages (1919). To Huizinga, whose research focused on France and the Low Countries rather than Italy, despair and decline were the main themes, not rebirth . </P> <P> Modern historiography on the period has reached a consensus between the two extremes of innovation and crisis . It is now generally acknowledged that conditions were vastly different north and south of the Alps, and the term "Late Middle Ages" is often avoided entirely within Italian historiography . The term "Renaissance" is still considered useful for describing certain intellectual, cultural, or artistic developments, but not as the defining feature of an entire European historical epoch . The period from the early 14th century up until--and sometimes including--the 16th century, is rather seen as characterized by other trends: demographic and economic decline followed by recovery, the end of western religious unity and the subsequent emergence of the nation state, and the expansion of European influence onto the rest of the world . </P> <P> The limits of Christian Europe were still being defined in the 14th and 15th centuries . While the Grand Duchy of Moscow was beginning to repel the Mongols, and the Iberian kingdoms completed the Reconquista of the peninsula and turned their attention outwards, the Balkans fell under the dominance of the Ottoman Empire . Meanwhile, the remaining nations of the continent were locked in almost constant international or internal conflict . </P>

Who took the lead in extending european influence in the 1400s