The first historical records on Aalst date from the 9th century, when it was described as the villa Alost, a dependency of the Abbey of Lobbes. During the Middle Ages, a town and port grew at this strategic point, where the road from Bruges to Cologne crossed the Dender. In the 11th century, Aalst was transferred from the pagus of Brabant to the County of Flanders. Its frontier position on the border of the Holy Roman Empire allowed the town to keep a certain degree of independence. Its relation with Brabant has been preserved in the city�s white and red coat of arms, the colours of Lotharingia.
Construction of the town hall began in the middle of the 12th century, making it the oldest surviving town hall in Belgium. Several manuscripts from this period still survive in the town archives. The town hall, and the city itself, were almost entirely destroyed by fire in 1360. The town was soon rebuilt and a new belfry in gothic style was built in the 15th century. This was a time of great prosperity for the city, dominated by the powerful weavers' guild. It is also at that time that Dirk Martens, a local citizen, became the Southern Netherlands� first printer, founding a printing shop in 1473 that published books by various authors including Christopher Columbus; Martens would later become a professor at the Catholic University of Leuven.
Aalst suffered considerably under the Eighty Years' War (1568�1648). It was later taken by the French Marshal Turenne in the War of Devolution of 1667, then occupied by France until 1706 along with Southern Flanders in general. The textile-based economy flourished under the French. The 19th century was marked by social crises engendered by the Industrial Revolution, with Father Adolf Daens and his Christene Volkspartij emerging as the local defender of workers' rights. The 20th century was marked by occupation by the Germans during both world wars. the cities citizenry are known as the onions, the origin of the name can
