The term "spice trade" refers to a long history of trade that existed between Northeast Africa, Asia and Europe for thousands of years. It began as early as 3000 BC, as evidence has been found in the Kerala region of India that it had already been established as a center of the trade around that time.
The trade consisted of all sorts of things but a large part of the early focus was on spices like cinnamon, turmeric, ginger, pepper and cardamom. Because these spices were in demand all over the known world at that point, the trade in those spices served to establish trading routes that were also used for other things like opium and other goods.
The spice trade has been associated with the development of the Great Silk Road and other overland routes between Africa, Asia and Europe, and also helped to spur the development of ocean routes around the Cape of Good Hope and throughout the Indian Ocean.