The Battle of the Teutoburg Forest, described as the Varian Disaster by Roman historians, was a major battle between Germanic tribes and the Roman Empire that took place somewhere near modern Kalkriese from September 8–11, 9 AD, when an alliance of Germanic peoples ambushed three Roman legions led by Publius Quinctilius Varus and their auxiliaries. The alliance was led by Arminius, a Germanic officer of Varus's auxilia. Arminius had acquired Roman citizenship and had received a Roman military education, which enabled him to deceive the Roman commander methodically and anticipate the Roman army's tactical responses.

The Germanic peoples were historical groups of people that once occupied Northwestern and Central Europe and Scandinavia during antiquity and into the early Middle Ages. Since the 19th century, they have traditionally been defined by the use of ancient and early medieval Germanic languages and are thus equated at least approximately with Germanic-speaking peoples, although different academic disciplines have their own definitions of what makes someone or something "Germanic". The Romans named the area belonging to North-Central Europe in which Germanic peoples lived Germania, stretching east to west between the Vistula and Rhine rivers and north to south from southern Scandinavia to the upper Danube. In discussions of the Roman period, the Germanic peoples are sometimes referred to as Germani or ancient Germans, although many scholars consider the second term problematic since it suggests identity with present-day Germans. The very concept of "Germanic peoples" has become the subject of controversy among contemporary scholars. Some scholars call for its total abandonment as a modern construct since lumping "Germanic peoples" together implies a common group identity for which there is little evidence. Other scholars have defended the term's continued use and argue that a common Germanic language allows one to speak of "Germanic peoples", regardless of whether these ancient and medieval peoples saw themselves as having a common identity. While several historians and archaeologists continue to use the term "Germanic peoples" to refer to historical people groups from the 1st to 4th centuries CE, the term is no longer used by most historians and archaeologists for the period around the Fall of the Roman Empire and the Early Middle Ages.