One important reason was the need to overcome the expensive eastern trade routes, dominated first by the republics of Venice and Genoa in the Mediterranean, and then controlled by the Ottoman Empire after the conquest of Constantinople in 1453, barring European access, and going through North Africa and the historically important combined-land-sea routes via the Red Sea. Both spice and silk were big businesses of the day, and arguably, spices which were used as medicine, drugs and preservatives was something of a necessity—at least to those Europeans of better than modest means.