books.google.fr - Henri Pirenne is best known for his provocative argument--known as the "Pirenne thesis" and familiar to all students of medieval Europe--that it was not the invasion of the Germanic tribes that destroyed the civilization of antiquity, but rather the closing of Mediterranean trade by Arab conquest in...http://books.google.fr/books/about/Medieval_Cities.html?hl=fr&id=j_WTgGU8PkoC&utm_source=gb-gplus-shareMedieval Cities
