Leading campaigns involving tens of thousands of troops, in 127 BCE the Han general Wei Qing (d. 106 BCE) recaptured the Ordos Desert region from the Xiongnu and in 121 BCE Huo Qubing (d. 117 BCE) expelled them from the Qilian Mountains, gaining the surrender of many Xiongnu aristocrats. At the Battle of Mobei in 119 BCE, generals Wei and Huo led the campaign to the Khangai Mountains where they forced the chanyu to flee north of the Gobi Desert. The maintenance of 300,000 horses by government slaves in thirty-six different pasture lands was not enough to satisfy the cavalry and baggage trains needed for these campaigns, so the government offered exemption from military and corvée labor for up to three male members of each household who presented a privately bred horse to the government.