Answer:
True
Explanation:
The topography of the European continent is mostly flat, especially in the Eastern part of the continent where the Northern European Plain becomes the immense Russian steppe that is only separated from Asia by the Ural Mountains.
This open topography has made the continent vulnerable to invasion until recently. This is why Huns in the Late Antiquity, and the Mongols in the Middle Ages, were able to sweep the continent coming from the same place: Mongolia.
