[Telepathic Intruder]

The densely forested hills of Germany, the only break in the plains of northern Europe between the Pyrenees mountains and the Volga basin, was probably the only thing preventing the Romans from further conquest.

[Fiji Hill]

The densely forested hills of Germany, the only break in the plains of northern Europe between the Pyrenees mountains and the Volga basin, was probably the only thing preventing the Romans from further conquest.

They may have also discouraged the Mongols, coming from the other direction, from moving farther west when they invaded Eastern Europe in 1241.