Since Joseph de Guignes in the , modern historians have associated the Huns who appeared on the borders of Europe in the with the Xiongnu who had invaded China from the territory of present-day Mongolia between the and the . Due to the devastating defeat by the Chinese Han dynasty, the northern branch of the Xiongnu had retreated north-westward; their descendants may have migrated through Eurasia and consequently they may have some degree of cultural and genetic continuity with the Huns. Scholars also discussed the relationship between the Xiongnu, the Huns, and a number of people in central Asia who were also known as or came to be identified with the name "Hun" or "Iranian Huns". The most prominent of these were Chionites, the Kidarites, and the Hephthalites.