This particular Elephant Armour was used last in 16th century by the Rajput warrior clans of India

These kinds of armours were first documented in the accounts of Meghasthenes' indica where he talked about how alexander and selecus was in awe looking at those humongous armoured elephants during his battle woth porus which was an extremely close fight, after defeating porus one of the reasons why he did not advanced more inside India was dhana nandas humongous army which had 200,000 infantry, 20,000 cavalry, 2,000 four-horsed chariots and 3,000 armoured elephants. So it is safe to say that these kinds of armoured elephants were in use from at least 326 BC (documented) to 16th century