Seine-et-Oise was a department in the Île-de-France region of northern France. Established during the French Revolution in 1790, it was named after the Seine and Oise rivers. The department was known for its diverse landscapes, including urban areas, forests, and agricultural land. In 1968, Seine-et-Oise was divided into several smaller departments, including Yvelines, Essonne, and Val-d'Oise. This reorganization aimed to improve local governance and administration. Today, the historical significance of Seine-et-Oise remains, as it played a crucial role in shaping the modern structure of the Île-de-France region.