For most of human history, international trade was based on several commodities: slaves, gold, silk... and spices. Of these, spices were probably the most significant. With salt and spices, food could be preserved and kept for longer periods, or at least have the taste of spoilage concealed with strong flavors, with the most desired spices in Europe being pepper, cinnamon, saffron and ginger.
In the Middle Ages, the Venetians enjoyed a near to unrivaled domination of the spice market through their ties with the (formerly Roman) Byzantines and (later) the Mongols. Spices, however, were also the catalyst for global Western imperialism as following the fall of Byzantium in the late 15th century, the old trade routes to India and the Malay Archipelago (the primary sources for spices) were cut and European powers began to seek ways to circumvent them.