Fig. 2: The bronze horses and some other bronze artifacts unearthed in the Yanjiagou tomb.

a The GQ744-1 bronze horse. b The GQ744-2 bronze horse, its right front leg exhibits a stratified structure, comprising an outer layer of metal, followed by dark-red and yellowish-brown hardened substances, and finally filling soil. c Some other bronze artifacts unearthed, including vessels (Ding, Gui, Yan, Gu, You) and weapons (Yue, Ge, sword, knife).