I have an edition of the Nibelungenlied, which presents a modern German translation right next to a version of the original text. While the original is somewhat difficult to understand there is an amazing continuity between the two.

To me this made it clear that the German Nation has been clearly defined over the last thousand years and just how similar the people who wrote and enjoyed that work are to the native Germans right now. Can only recommend people do something like that if they want to dispel the delusion that people of your Nation who lived a thousand years ago were in any way fundamentally different from you.