Germania (Greek: Γερμανία) was the Ancient Greek and Latin geographical term for the regions inhabited by mainly by peoples considered to be Germanic. It was most often used to refer especially to the east of the Rhine and north of the Danube River.
The Roman Empire, in their attempts to conquer the region, designated two sub-territories: Lesser Germania and Greater Germania. While Lesser Germania was largely pacified by Rome, Greater Germania was not. The last major attempt was halted by the disastrous Battle of the Teutoburg Forest, which saw three Roman Legions wiped out. Emperor Augustus ordered the withdrawal from Greater Germania. This would be a fatal decision, as this allowed German tribes or "barbarians" to cause the downfall of the Empire a long time later.
While the ancient region of Germania does include modern Germany, it also includes parts of modern Belgium and the Netherlands. Thus, it has been made a separate article. When referring to the ancient region, Harry Turtledove has often used "Germany" and "Germania" interchangeably.
During the reign of Emperor Augustus, General Marcus Vipsanius Agrippa oversaw the successful conquest of Germania. In time, Germania became a fully Romanized province of the Empire, with several emperors, writers, and soldiers being of German descent.
The residents of the Roman town of Carnuntum despised the Germanic tribes in the neighbouring Germania, even though there were was lot of trade and contact with the latter. A modern time-traveller, Nicole Gunther, was the only person who knew that their descendants would be practically Germans but she didn't bother telling them.
They also feared the tribes and hated how the Germans swaggered through their town, as "if they owned it". In fact, Gunther actually witnessed the Germanic, specifically Marcomanni and Quadi, invasion of Carnuntum.
Marcus and Lucius had been stationed in Germany before being transferred to Palestine to help put down the Son of God's rebellion. Upon arrival, they remarked on how different the countries were. In Germany, the sun might never be seen for days at a time, whereas in Palestine it was out perpetually.