Here is the answer to your question:
the development of nationalism did not come about only through wars and territorial expansion . Culture played an important role in creating the idea of nation :art and poetry , stories and music helped express and shape nationalist feelings.
romanticism a cultural movement which sought to develop a particular form of nationalist feeling.
romantic artist and poets generally criticised the glorification of the reason and science and focused instead on emotions, intuition and mystical feelings.
their efforts was to create a sense of shared and collective heritage , a common cultural past as the basis of a nation.
a German philosopher Johann Gottfried Herder claimed that true German culture was to be found among the common people - das volk.
it was through folk songs, folk poetry and folk dances that the true spirit of the nation was popularised.
so, collecting and recording these forms of culture was essential to the project of nation building.