Overview
The silver mines are the reason people settled in the remote, isolated Vale Sangora in the first place. According to "The Secret History of Vale Sangora," a narrative lore document from Rebel Wolves, the surrounding mountains were rich with silver, and its "cold gleam lured men like moths to a fire." The rocky slopes are pockmarked with mine entrances, and the steady knocking of pickaxes echoed through the valley all day long.
Connection to Coen
Coen worked in the silver mines alongside his father since childhood. Years of prolonged exposure caused him to develop argyria, a real medical condition where silver accumulates in the body's tissues. This poisoning turned out to be the single most important factor in Coen's story: when vampires later attempted to turn him, the silver already present in his blood and flesh prevented the complete transformation. Instead of becoming a full vampire, Coen became a Dawnwalker, a being who is human during the day and vampiric at night.
Political significance
Knyaz Skender Dragosti, the human lord who ruled Vale Sangora before Brencis seized power, used proceeds from the silver mines to expand the dungeons beneath Greifberg castle. He chose military construction over religious or civic investment, which gives some insight into the kind of ruler he was. The wealth generated by the mines made Vale Sangora worth conquering, and Brencis's takeover was at least partly motivated by control of these resources.
The valley's isolation
Vale Sangora sits deep within the Carpathian Mountains, accessible only through narrow gorges and only during summer months. The silver mines are what drew settlers to endure this isolation. The combination of mineral wealth, geographic remoteness, and the Black Death sweeping through Europe in 1347 created the perfect conditions for the Vrakhiri vampires to establish dominance over a population with nowhere to flee.