This is a complex question, mainly because Germany as an entity did not exist until 1871. Your first step in answering the question is to ask yourself whether you are looking for special traditions of one particular state (Bavaria, Prussia, etc.) or common traditions that might have facilitated unification.
Many of the philological studies of northern Europe in the 19th century were devoted to precisely this quest for some overarching unifying linguistic and cultural tradition. (see Olender). In the emerging discipline of folklore, this took the form of searching for traditional oral stories and myths that formed a shared substrate to the national consciousness of the people (volk).
In philology, this took the form of the Indo-European hypothesis, which traced the history of Indian, Greek, Latin, and European languages and religion back to a common ancestor. Max Muller attempted to link Indo-European languages to a common sun god, and was the main source of the argument for the commonality among the German (and Nordic) states of a shared Aryan heritage. His work, unfortunately, was later (mis)appropriated by the Nazis.