The Gnummor Stele

The Gnummor Stele is a relief carving in stone which most sages believe is dated from the early 4th Age, and depicting a pre-cataclysmic scene from the 3rd Age. This stele is in place at the Plaza of Liberation in the City of Treft. 

While early studies of it assumed it was made in the 3rd Age during the height of the Gnomish Era, recent scholarship agrees on the latter date given the polemical nature of the depiction of the Gnomes (background) themselves.