Scientific fellows of the Institute of Archaeology and the Institute of History of the Mongolian Academy of Sciences along with the Department of Archaeology and Anthropology of the National University of Mongolia and the National Museum of Mongolia have contributed to this work. This encyclopedia represents the largest ever comprehensive collection of studies on Xiongnu Civilization and the first work in which a complete millennia of the Mongolian History is centered on the Xiongnu. Thus, this work is not merely limited to discussions of history, culture and imperial expansion of the Xiongnu political entity during the 3rd century BCE to 2nd century CE, it also covers the subsequent periods and cultures, such as the Xianbei, Rouran (Nirun) and ancient Tuerks, whose nomadic polities drew significantly upon the Xiongnu heritage. In particular, this work touches upon the important post-Xiongnu period of nomadic states and historical figures of the 2nd-4th centuries CE, which has rarely been directly addressed until now. This work, though compiled by the efforts of scholars within Mongolia, represents growing efforts to expand the chronological and geographical scopes of Xiongnu historical and archaeological investigations beyond previous limitations of the formal imperial period and boundaries of the modern nation of Mongolia in order to more fully understand the Xiongnu historical phenomenon.