Tools lithiques, whose axes polished of Neolithic time as well as " villae Gallo-Romans ", agricultural establishment, give evidence of the age of the human setting-up.
XL'activité potière au XIème siècle était présente après découverte de fours.
Lassy 95 est citée dès le XIIème siècle, lorsque Renaud II, conte de Clermont, seigneur de la moitié de Luzarches, fait don aux moines de l'abbaye Saint-Martin-des-Champs de la moitié des dîmes.
Pendant la guerre de 100 ans, vers 1420, le village subit de gros dommages, il est ruiné par les Anglo-Bourguignons.
In 1899, the main economic activity of the municipality of Lassy is the manufacturing of chairs and stools, which furnish churches and cabarets of Paris and neighborhood.
Forks, wooden rakes and broomsticks are exported in other departments and abroad.
Historic witnesses of Lassy
- The church of Nativité-de-la-Sainte-Vierge - XIIIème-XVIème century:
The church underwent grave damage during the Hundred Years' War. Parts of the XIIIth century always exist. The building was rebuilt in the XVIth century.
- The Mill of Lassy:
The former mill with which the energy was supplied by Ysieux, belonged to the economic network of the valley since the Middle Ages.
- The hall of farm:
One of the farms of Lassy kept his hall, higher than wide. He allowed to bring in in hitched cart a big volume of thatch. The straw was then stored in barns for the litter of animals. At the end of the XXth century an only big farm remains.