Short answers, pulled from the story.
Germania was a large historical region in north-central Europe during the Roman era, associated by Roman authors with the Germanic peoples. Roman geographers described it as stretching from the Rhine in the west to the Vistula in the east, and from the Upper Danube in the south to the known parts of southern Scandinavia in the north.
Julius Caesar was the first Roman writer to apply the name Germania to the territory east of the Rhine, using it during the Gallic Wars of the 1st century BC. The Romans appear to have borrowed the term from the Gauls. The Latin name Germania means "lands where people called Germani live," but the etymology of Germani itself remains disputed, with Celtic, Germanic, Illyrian, and Latin origins all proposed.
Rome's campaign to extend control to the Elbe was decisively stopped by Arminius at the Battle of the Teutoburg Forest in AD 9. The Roman emperor Augustus had created the short-lived province of Germania Antiqua in 7 BC and planned a larger province of Magna Germania, but the defeat ended those ambitions and the Rhine became the permanent imperial border.
Roman Germania referred to the provinces of Germania Inferior and Germania Superior, established in northeast Gaul west of the Rhine under direct Roman rule. Magna Germania, also called Germania Libera or Germanic Barbaricum, was the large territory to the east that remained independent of Roman control throughout the imperial period.
From the 3rd century AD, Germanic confederations including the Alemanni and Franks raided Roman Germania repeatedly. In 406, large numbers of people fleeing the Huns crossed the Rhine from Magna Germania into Roman territory, accelerating the collapse of Roman rule. Germanic peoples subsequently played a major role in dismembering the Western Roman Empire, which fell in the 5th century AD.
The name of Germany in English and many other languages is derived directly from the Latin name Germania. The word is attested in Old English translations of Bede and Orosius, and since the 17th century the most common English name for Germany has traced back to this Roman geographic term.