From the Gallo-Romans to the Frankish kings
A Roman road likely connected Rouen to Beauvais, passing through Lyons, Lilly, Morgny, and Bézu. Lilly (Lilliacum), Fleury, Morgny and Lyons bear names of Gallo-Roman origin, and the soil has yielded tiles, sarcophagi, columns, bas-reliefs and coins, from Nero to Trajan. In Lyons itself, in the Bout-de-Bas district, Dr. Marc-Adrien Dollfus uncovered a Gallo-Roman theater built into the hillside, active until the 3rd century.
Heir to imperial laws, the forest remained state-owned: a timber and hunting reserve, it would remain so throughout its history. Clotaire II and Dagobert, who resided in Étrépagny, undoubtedly hunted there. Charles the Bald and Carloman II resided in a palace calledBasiu, located in Bézu, at the current manor of La Fontaine-du-Houx. According to the chronicle of Saint-Bertin, Carloman was mortally wounded there while hunting in 884, in the forest of Bézu, the former name of the Lyons forest.