Ewald Fettweis (1881-1967) was the first researcher to develop and establish the term ethnomathematics. This article presents his contribution to ethnomathematics and its development as a scientific theory. We will show that he was the first researcher to realize and practice ethnomathematics in his research and to explain it in his lectures, thus giving a disciplinary status to ethnomathematics. Fettweis's conceptualization of ethnomathematics was developed in the 1930s, much earlier than Ubiratan D'Ambrosio's subsequent, independent introduction of the same term. Based on this work, we argue for the existence of a pre-paradigm period in the development of ethnomathematics.