Henri Pirenne (1862-1935) was a Belgian historian and Orientalist.
He was born on 22 December 1862 in Verviers as the oldest of eight children. His father was Lucien Henri Pirenne (worked in the textile industry) and his mother was Virginie Duesberg. He studied at the local "Collège communal" and later at the "Athénée royal". The highlight of his school life was his reading in public aged only 16 of a poem to the Belgian monarch of the time, King Leopold II who was in Verviers in 1878 for an official opening.
In October 1879, he continued his studies at Liège University where he obtained a doctorate in 1883 with a study on the medieval history of Dinant. His father wanted him to become an engineer but his obvious mathematical talents and his strong interest in medieval history meant he did not follow that particular avenue. In 1884, he studied in Leipzig with the historian William Ferdinand Arndt ( 1838-1895) and in Berlin with the historians Harry Bresslau (1848-1926) and Gustav Schmoller. He then spent the 1885 academic year in Paris at the "École des Chartes" and the "École Pratique des Hautes Études". The following year he became Professor of Medieval and Belgian History at Ghent University where he stayed until the end of his teaching career in 1930, becoming Chair in 1899. He was arrested in 1916 by the German army for refusing entry to the University. He was taken first to Krefeld, then to Holzminden and finally to Kreuzburg. He was not released until November 1918. During his stay in Kreuzburg, he wrote "History of Europe" which was not published until after his death on 24 October 1935 in Ukkel, near Brussels.
Other major works by Pirenne include "Medieval Cities" (1925) and "History of Belgium" (1900-32).
However, he was best known for the Pirenne Thesis, explained in detail in his work "Mohammed and Charlemagne" (1937). Pirenne was convinced that the ancient world ended and the Middle Ages began not with the Germanic invasions but with the destruction of trade and urban life following the establishment of Muslim control over the Mediterranean Sea.
His Thesis can be summarised as follows :
The Roman Empire was fundamentally a maritime empire oriented around the Mediterranean Sea. There were of course non-maritime frontiers in the wooded north of Europe and the deserts of the Sahara and the Middle East but most, if not all, were within the watershed of the Mediterranean Black Sea. The sea not only provided the routes for political administration and military supervision but also for trade. Sea trade was predominantly in the hands of merchants from the Levantine, the Syrians and Jews. This trade made possible regional specialisation and economies of scale. Not only were goods provided cheaper as a result of this trade but there was a vastly larger variety of goods available.
The Germanic tribes in the West were becoming Romanised. Germans served in the Roman Army and sometimes Germans commanded the armies of Rome. Thus the conflicts in the West were not civilization versus barbarians but instead Romanized Germans fighting against Germanized Roman armies. The battles in the East were a different matter; there it was Roman culture versus Parthian (Persian) culture. Losses in the West could be regained by diplomacy or military operations, but losses in the East were permanent. Thus the shift of administration from Rome to Constantinople reflected this situation.
When Moslims captured the Mediterranean in the seventh century the trade routes were cut. The Vikings later also made sea trade difficult. The Magyars swept into Europe out of Central Asia and further cut trade in the east. The net result is that individual regions could not count on producing some goods for market and using the proceeds from their sale to buy the other goods which were needed. Each region had to be self-sufficient.
Self-sufficiency has its attractions but with self-sufficiency you lose the gains from specialisation and the economies of scale. Living standards decline so there may not be any market for trading goods even if they were available. The surpluses that could support some elements of the society pursuing cultural activities disappeared and almost everyone had to work for a living.