"The Horde" was a Boxed-set campaign setting for D&D, released by TSR in 1990 to add Mongolians (called the Tuigan) to the Forgotten Realms. The boxed set describes the area known as the Endless Wastes- you'll generally find it in the far north-east of your maps of Toril.
The boxed set describes a range of cities, cultures, and customs, including water-breaking-rock style kung fu, a Great Wall with the bound soul of a dragon desperately trying to escape, and most importantly rules for the Shatjan - a race of short half-men with the head of a reindeer, who eat grass and have an icy breath weapon. It also includes stats for Yamun Kahan, a red-headed brutal nomad warlord who is both a brilliant strategist, and who has united the clans.
Apparently Genghis motherfucking Khan was a L17 Fighter.