A lot, the period from National Romanticism onward is the most relevant for any form of study of a "nation".

Before that you could only think in terms of loosely connected realms/kingdoms, before more in terms of tribes and some city-states. Those aren't that useful to study to understand the present, from the 17th century is where most of the current culture branched out from.

The historical connection to the land from the people/tribes living in territories of modern Europe from before the Middle Ages is more akin to studying Native Americans in the USA, they were the people inhabiting the land, they had their traditions, and some of those traditions were used to forge the national identity of present cultures but there's a lot of this national identity that was myth-making by National Romantics to generate a sense of unity needed for creating the nation and nation-states.