Before Europeans found a sea route to Asia, the high cost of spices in Europe was primarily due to the complex trade networks that involved many merchants and middlemen, which significantly increased prices. Spices were highly sought after for their use in cuisine, preservation, and medicine, but the overland trade routes, such as the Silk Road, passed through various regions and required multiple transactions. Each merchant along the way added their markup, resulting in skyrocketing prices by the time the spices reached European markets.
While the geopolitical climate, including the control of trade routes by empires like the Ottoman Empire, was also a factor, it was the intricate web of trade that primarily drove up costs.