The appearance of the chess pieces had altered greatly since the times of chaturanga, with ornate pieces and chess pieces depicting animals giving way to abstract shapes. This is because of a Muslim ban on the game's lifelike pieces, as they were said to have brought upon images of idolatry. The Islamic sets of later centuries followed a pattern which assigned names and abstract shapes to the chess pieces, as Islam forbids depiction of animals and human beings in art. These pieces were usually made of simple clay and carved stone.