Nubia had become a vital trade route for Egypt, providing a corridor between Egypt and tropical Africa. This can be seen by 3100 BC, a period when Egyptian craftsmen were able to use ivory, ebony, and special woods that came through Nubia from tropical Africa. Egyptians imported gold, incense, ebony, ivory, and exotic animals from tropical Africa through Nubia. As trade between Egypt and Nubia increased, so did wealth and stability.