The Irdin Manha Formation is a geological formation from the Eocene located in Inner Mongolia, China, a few kilometres south of the Mongolian border.

Andrewsarchus is an extinct genus of ungulate that lived during the Middle Eocene in China. It contains two species, A. mongoliensis and A. crassum. It was formerly placed in the families Mesonychidae or Arctocyonidae, but is now the sole member of a distinct family, Andrewsarchidae. Only known from a largely complete skull as well as isolated teeth, It is notable for being estimated as the largest terrestrial, carnivorous mammal, but that status has been disputed.