Henri Pirenne (1862-1935) was a leading Belgian historian. He was a leader of the non-violent resistance against the Germans occupying Belgium in World War I.

He is most famous today for two contributions to European history: what has become known as the Pirenne Thesis, concerning when the Middle Ages starts, and a distinctive view of Belgium's medieval history.

Henri first developed his ideas for the Pirenne Thesis in a series of papers in 1922-1923, and then spent the rest of his life refining it with supporting evidence. The most famous exposition of the Pirenne Thesis can be found in his book Mohammed and Charlemagne first published in 1937 (1939 in English).

Traditionally the Middle Ages were seen to start with the fall of the Roman Empire in the 5th century, a theory Edward Gibbon had famously put forward in the 18th century. Pirenne challenged the notion that German barbarians had caused the Roman Empire to end, and he challenged the notion that the end of the Roman Empire should be equated with the end of the office of Emperor in Europe, which had occurred in 476. He pointed out the essential continuity of the economy of the Roman Mediterranean even after the barbarian invasions, that the Roman way of doing things did not fundamentally change in the time immediatly after the "fall" of Rome. Barbarians came to Rome not to destroy it, but to take part in its benefits, they tried to preserve the Roman way of life.

According to Pirenne the real break in Roman history occurred in the 7th century as a result of Arab expansion. Islamic conquests of Spain and North Africa, the area of todays Turkey, Syria and Palestine, ruptured economic ties to Europe, cutting the continent off from trade and turning it into a stagnent backwater with wealth flowing out in the form of raw resources and nothing coming back. This began a steady decline and impoverishment so that by the time of Charlemagne Europe was entirely agrarian at a subsistence level with no long distance trade. Pirenne says "Without Islam, the Frankish Empire would have probably never existed, and Charlemagne, without Muhammad, would be inconcievable".

Pirenne used quantative methods in relation to currency in support of the thesis. Much of his argument is built upon the disappearance of items from Europe, items that would have to be obtained from outside Europe. For example the minting of gold coins north of the Alps stopped after the 7th century, indicating a loss of access to wealthier parts of the world. Papyrus, only made in Egypt, was no longer found north of the Alps after the 7th century, writing reverted to animal skins, indicating an isolation from wealthier areas.

Pirennes Thesis is not without critics. One does not have to entirely accept or deny his theory without finding useful elements for understanding the period; and it provides a new way at looking at periodization schemes that are often seen as accepted fact.

His other major idea concerned the nature of medieval Belgium. Belgium as an independent nation state had been brought into being only a generation before Pirenne's birth; throughout Western history, its fortunes had been tied up with the Low Countries, which now include the Netherlands, Luxembourg and parts of north-east France. Furthermore, Belgium lies athwart the great linguistic divide between French and Dutch. The unity of the country could be thought accidental, something which Pirenne sought to disprove in his History of Belgium (1899-1932). His ideas here have also proved controversial, with many historians preferring to stress the economic unity of the Low Countries as a whole.

References

• Hodges, Richard and David Whitehouse. Mohammed, Charlemagne, and the origins of Europe. Cornell University Press. 1983. ISBN 0801492629 - influential analysis of the Pierenne Thesis and the role of recent archaeological findings.
• McCormick, Michael. Origins of the European Economy: Communications and Commerce, 300-900. Cambridge University Press. 2001. ISBN 0521661021 - a reexamination of the Pierenne Thesis.
• Pirenne, Henri. Mohammed and Charlemagne. Dover Books, 2001. ISBN 0486420116 - a recent reprint of the 1937 classic.