Answer:
The ivory trade is the commercial, often illegal trade in the ivory tusks of the hippopotamus, walrus, narwhal,mammoth,and most commonly, African and Asian elephants.

Ivory traders, c. 1912
Ivory has been traded for hundreds of years by people in Africa and Asia, resulting in restrictions and bans. Ivory was formerly used to make piano keys and other decorative items because of the white color it presents when processed but the piano industry abandoned ivory as a key covering material in the 1980s in favor of other materials such as plastic. Also, synthetic ivory has been developed which can also be used as an alternative materials for making piano keys.