Wootz steel is a steel characterized by a pattern of bands or sheets of micro carbides within a tempered martensite or pearlite matrix. It is the pioneering steel alloy matrix developed in South India in the sixth century BC and exported globally. It was also known in the ancient world as Seric Iron.
The Wootz steel originated in India. There are several ancient Tamil, Greek, Chinese and Roman literary references to high carbon Indian steel since the time of Alexander's India campaign. The steel was exported globally, and was termed the finest steel in the world, i.e. Seric Iron to the Romans, Egyptians, Chinese and Arabs by 500 BC. The steel was exported as cakes of steely iron that came to be known as "Wootz".
The Tamilakam method was to heat black magnetite ore in the presence of carbon in a sealed clay crucible inside a charcoal furnace. An alternative was to smelt the ore first to give wrought iron, then heated and hammered to be rid of slag. The carbon source was bamboo and leaves from plants such as Avārai.The Chinese and locals in Sri Lanka adopted the production methods of creating Wootz steel from the Indians by the 5th century BC, this early steel-making method employed a unique wind furnace, driven by the monsoon winds, capable of producing high-carbon steel.
The Arabs introduced the Indian Wootz steel to Damascus, where an industry developed for making weapons of this steel. The 12th century Arab traveler Edrisi mentioned the "Hinduwani" or Indian steel as the best in the world. Another sign of its reputation is seen in a Persian phrase – to give an "Indian answer", meaning "a cut with an Indian sword". Wootz steel was widely exported and traded throughout ancient Europe and the Arab world, and became particularly famous in the Middle East.