Metallurgy

In the 5th century BC, the Indian Army used arrows tipped with iron. They were also using other armourary made up of iron.

 Greek historian Herodotus observed that several objects stood testimony to the higher level of metallurgical knowledge achieved by ancient Indians.

 

 The Iron Pillar near the Qutub Minar in Delhi was cast in the Gupta Period around circa 500 AD. The pillar is 7.32 metres tall and weigh 6 tonnes. For last 1500 years, it has not rusted despite being out in the open. This shows the knowledge of rust proof iron still in use.