High Quality Content by WIKIPEDIA articles! Sagy is a commune in the Val-d'Oise department in Île-de-France in northern France. Val-d'Oise (French pronunciation: [val dwaz]) is a French department named after the Oise River, located in the Île-de-France region. Paris-Charles de Gaulle Airport, France's main international airport is partially located in Roissy-en-France, a commune of Val d'Oise.Val-d'Oise was created when the former departments Seine and Seine-et-Oise were broken up into six departments in 1968.In descending order, the largest communes (over 25,000 population as of the 1999 census) are: Argenteuil, Sarcelles, Cergy, Garges-lès-Gonesse, Franconville, Ermont, Pontoise, Goussainville, Bezons, Villiers-le-Bel, Taverny, and Sannois.