Of many potters their years of production are known, thus providing a terminus
post quem for the layer in which the stamped object was found.
Beside that, the Samian ware often was lavishly decorated with very specific
geometric patterns and typical animals and flowers. These decorations also
may provide an indication about the potter of the object.
In Valkenburg, a tremendous amount of high-quality Samian ware was excavated. Valkenburg was a relatively 'early'
site (from 40 AD on). On the other hand, the Batavian revolt of 69 AD very clearly shows
in the stratigraphy as a
thin dark layer with much charcoal and other burnt remains. All the selected finds are from below this
layer that acts as a terminus ante quem, and therefore the finds are from before 69 AD.