We don't know when and exactly what circumstances the Aryans left their homes in the lofty table lands of Central Asia.  As mentioned in my last post, according to Bayard Taylor, this was a mixed group of people including Hindoos, Persians, Greeks, Romans, Celts, and Slavonic tribes. Most scholars believe that there were different migrations and that each movement westward was accomplished slowly. Again, according to Taylor, this would take place before Greece or Italy had been established. 

However, according to "The Early Germans" by Malcolm Todd, "at some date, probably about 320 BC, Pytheas of Marseilles sailed around Britain and along northern European coast (possibly rounding Jutland and entering the western Baltic). His journey was so astonishing an achievement that contemporary and later writers refused to believe his account, and what survives of it amounts only to quotations by others . Much of what Pytheas is said to have recorded is geographically reliable, though it is scanty on northern European main land. He is chiefly of interest because he may have been the first Mediterranean observer to distinguish the Germanoi from  Keltoi." 

Picture from History.com 

Keltoi is referring to the Celts. Herodotus , a fourth century BC writer and geographer, relates that they were the most western of European peoples and that the Danube had its source in their territory. But he makes no mention of the Germans. 

While one historian claims that Germans were not yet established, another is saying there is evidence that they actually were. Thank goodness for multiple resources. I'm thinking that this time is a bit fuzzy for most historians. There isn't much information on Germans during this period and Todd claims that the Germans were relative latecomers to history. So, moving onward!!