According to Ahmed (2014), Harappan oven structures may have operated in a similar manner to the modern tandoors of the Punjab.[51] The tandoor is traditionally made of clay and is a bell-shaped oven, set into the earth and fired with wood or charcoal reaching high temperatures. According to Hayter (1992) the original versions of the tandoor "in the Punjab, a province in the north-west of India, were sunk neck deep in the ground".