Xiongnu invasion of Donghu was a conflict between the Xiongnu and Donghu when Modu Chanyu came to power by ordering his men to kill his father in 209 BC. Modu Chanyu used the perceived weakness of the Xiongnu to his advantage[4] and defeated the Donghu Confederation, killing their leader and taking a great number of prisoners and livestock.[3][5]
^Bryan K. Miller, Power Politics in the Xiongnu Empire, p. 80
Sources
Barfield, Thomas J. (1989). The Perilous Frontier: Nomadic Empires and China 221 B.C. to AD 1757 (Studies in Social Discontinuity). Blackwell. ISBN1-55786-043-2.
Sinor, Denis (2008) [1990]. The Cambridge History of Early Inner Asia. Cambridge: Cambridge University Press. ISBN9781139054898.
Kim, Hyun Jin (2015). The Huns (PDF). Oxford: Routledge. ISBN9781317340911.