Why was the Vistula River an important trade route during the Roman Empire?

During the Roman Empire, the Vistula River served as one of the principal trade routes leading into central Europe. It functioned as a vital component of the extensive trading network known as the Amber Routes, which facilitated the movement of goods across the continent.12

Specifically, the river was a key segment of the Baltic-Pontus road, a major trade artery that followed the course of several eastern rivers to connect different regions. By providing a navigable waterway, the Vistula enabled the transport of valuable commodities, most notably amber, which was moved from northern Europe toward the south. This period also marks the first historical references to the river by Classical geographers such as Pliny, Tacitus, and Ptolemy, reflecting its growing significance to the Roman world.21