Complex sentence: Dacia also possessed salt, iron, silver and copper mines, dating back to the period of the Dacian kings, while the region also held large quantities of building-stone materials, including schist, sandstone, andesite, limestone and marble.
Split into simpler sentences: Dacia also possessed salt, iron, silver, and copper mines dating back to the period of the Dacian kings. The region also held large quantities of building-stone materials, including schist, sandstone, andesite, limestone, and marble.