The most extensive collection of Mongolian ethnographica in Europe goes back to the Austrian explorer Hans Leder (1848–1921). In 1892, his entomological studies led him from southern Siberia to Northern Mongolia. During further stays in Mongolia between 1892 and 1905, Leder collected and studied mainly Mongolian-Buddhist ritual items. A portion of his extensive collection is housed in the Museum of Ethnology Vienna, with further parts preserved in the major museums of ethnography in Germany, the Czech Republic and Hungary. This volume, based on a project report, releases previously unpublished archival data and depictions of museum artefacts, offers details about the collector’s biography and the intricate history of the collection, and discusses the artefacts’ iconography. The collection is unique as it represents a snapshot of everyday religious culture in Northern Mongolia at the turn of the 19th century. This part of Mongolian culture was increasingly repressed, and by the late 1930s it was nearly destroyed completely. The present publication also discusses the interaction with sacred artefacts and their meanings since the establishment of democracy in Mongolia in 1990.