The supposedly Indo-European groups seem to recede temporarily in Northern Europe and suffered a strong cultural "Danubianisation". In East Europe, the peoples beyond the Volga (Yamna culture), surely Indo-Europeans who were ancestors of the Iranian Scythians, took over southern Russia and Ukraine. In the Western world, the only sign of unity came from the Megalithic super-culture, which extended from southern Sweden to southern Spain, including large parts of southern Germany as well. However, the Mediterranean and Danubian groupings of the previous period appear to have fragmented into many smaller pieces, some of them apparently backward in technological matters. From 2800 BC, the Danubian Seine-Oise-Marne culture pusheed directly or indirectly southwards and destroyed most of the rich Megalithic culture of western France. After 2600 BC, several phenomena prefigured the changes of the upcoming period: