The history of Europe has been always been shaped by vast peoples marching from east to west.
Earlier this year, I did some reading about the collapse of the Roman Empire. One of the problems it faced was the pressure of peoples migrating west from the steppes of Asia. Some came on horseback, but many walked.. When these people arrived on the edge of the empire, the were initially held out by the border garrisons, but eventually the pressure became to great, and they invaded the Empire. Over a couple of centuries, the Tervingi, Grethuni, Vandals, Alans, Suevi, Goths, Burgundians, Visigoths and Ostrogoths arrived in Western Europe. Some travelled as far as France and Spain. The Vandals crossed into North Africa and conquered Carthage.
When they first arrived, these peoples were vicious warriors, but over time they settled down in their new land and gradually merged with the rest of the population. Most gradually converted to Christianity.
The same pattern of populations arriving from the east was held in check for several generations by artificial border created by the emergence of the national state, but now it is stirring again. It started with the collapse of the Soviet Union, when people from Eastern Europe began migrating to Western Europe. Polish painters and plumbers arrived into the United Kingdom looking for work.