In the long geological history of the Earth, humans first appeared during the Pleistocene Epoch, which dates back 1.6 million years to 10,000 years ago.
The invasions of Germanic groups led to a series of negative changes . Three effects of the Germanic invasions were halt on trade. Transportation of goods became unsafe. Less people were educated, and Europe no longer had one spoken language, unable to be understood by all.
Germany's invasion of Poland (September 1939) led Britain and France to abandon the policy of appeasement.
The policy of appeasement was signed by the prime ministers of Britain and France with Hitler in Munich in September, 1938. They had given in to Germany's annexation of the Sudentland as a German territory, including the evacuation of any Czech population from the region. After signing the Munich Pact, Hitler took control of all of Czechoslovakia (in March, 1939). Britain and France still did not pursue war with Germany when that happened. But when Germany invaded Poland in September, 1939, it was beyond clear that appeasing Hitler hadn't worked, and war was pursued.
Dropped the Atomic Bomb on Hiroshima and Nagasaki!