Gongs are common in Southeast Asia. Its early version, the ancient kettle gong, dates back to around 300 BCE. Gongs are of different sizes and shapes, either flat or with a center boss or knob. The bossed gong varies in diameter, shape, and depth of their rims, and the ways which they are being sounded. They can be found in Palawan, Mindanao, and Sulu archipelagos.