メルセン条約
Under the Franks, the name of the Chattuari was used for what became two early medieval gaus on either side of the Rhine, north of the Ripuarian Franks, whose capital was in Cologne. On the eastern side, they were near the Ruhr river, and across the Rhine they settled near the Niers river, between the Maas and the Rhine, where the Romans had much earlier settled the Germanic Cugerni. This western gau (Dutch: "Hettergouw", German: "Hattuarien") is mentioned in the Treaty of Meerssen, in the year 870 AD.