Passage: The Roman Empire had its centre in the Mediterranean, controlling all the countries on its shores; the northern border was marked by the Rhine and Danube rivers. Under emperor Trajan (2nd century AD) the empire reached its maximum expansion, controlling approximately 5,900,000 km2 (2,300,000 sq mi) of land surface, including Italia, Gallia, Dalmatia, Aquitania, Britannia, Baetica, Hispania, Thrace, Macedonia, Greece, Moesia, Dacia, Pannonia, Egypt, Minor Asia, Cappadocia, Armenia, Caucasus, North Africa, Levant and parts of Mesopotamia. Pax Romana, a period of peace, civilisation and an efficient centralised government in the subject territories ended in the 3rd century, when a series of civil wars undermined Rome's economic and social strength.

Question: What bordered the north?
Rhine and Danube rivers