It's hard for a person in today's atmosphere to walk into a discussion over Germany and the Roman Empire. The difficulty is that we all seem to want to view Germany from today's prospective, and simply skip out on the tribal concept that existed two thousand years ago.
In the period of 200 BC....what we view as Germany today.....was a wide-open area of trees, forests, and tribes. In the same fashion that we view ancient America and the tribal network that operated there two thousand years ago.....the tribal concept is best to use when viewing 'old' Germany.
Around 110 BC.....some Germanic tribes 'introduced' themsleves to Rome. The Cimbri and Teutones are groups which historians are a bit confused over today, and facts are limited. The Cimbri tribe appeared to be more of a pirate group who were never concreted to one particular area. The Teutones are referred to as Celtic in nature and come originally out of Jutland (Denmark or North Germany today).
Around 105 BC, the Battle of Arausio occurred in South France. For battle historians....this is one of the major battles in history. For the Romans.....a major defeat (roughly 80,000 troops die). For the Cimbri and Teutones.....this is the five-star moment.
Four years later....another battle in north Italy was a complete disaster for the Cimbri and Teutone tribes. After this point, Rome expands into the Germanic lands to a three-prong approach to handling tribes.
Oddly, you tend to see the same US three-prong approach to dealing with Indian tribes in the 1700s/1800s.
The three-pronged approach? Military expeditions, trade, and gifts.
To counter the tribal threats.....a "zone" was established. You pencil in most of Bavaria today, and edge the line up to just above Mainz, and then head westward toward Amsterdam. This is the area that the Romans would set up forts and ensure protection over their trade routes.
The trade side of the relationship? No matter where Romans when....trade was a major part of their civilization. If you came into the Mainz region.....grapes and wine were the chief element of trade. Other areas of Germany offered salt, glass, iron and lead. Spain offered gold, silver, tin and copper.
When you went past the Roman line of protection for trade in north Germany and toward the east.....you were mostly dealing for cattle, horses, and slaves.
The gift approach? It's similar to the American approach with Indian tribes. You'd walk into a tribal area with some gifts for the leadership....alcohol was always a top gift in ample proportions. You'd establish some type of relationship for safe passage or for trade,
The Cimbri and Trutone tribes both ended up giving up the pirate and continual movement attitude.....focusing more on a stable lifestyle eventually where trade was important.
By 476 AD.....Rome and it's empire had come to an end. The tribal environment had shifted over to a commercial trade situation and built their own forts. The trade trails (Limes)? They expanded out. Without the Roman soldiers, the trade routes were not exactly safe, but if you traveled in numbers.....that was the best choice for self-protection.
Oddly today, with EU regulations in place and the Euro currency....we've rebuilt the stabilization nature of the old Roman Empire, which has been dead for 1,500-odd years.