Complex sentence: Clay bullae matching to those in the Pratt collection were also uncovered, further demonstrating that the assemblage probably originated at this site, and had been removed illicitly and unloaded onto the antiquities market.
Split into simpler sentences: Clay bullae matching those in the Pratt collection were also uncovered. All of this evidence effectively demonstrated that the assemblage originated at this site, having been removed illicitly for sale on the antiquities market.