I am teaching ancient civilizations class to middle school students and I've reached the part of the curriculum of ancient India. It is among my favorite units that we cover because I find it interesting because I'm still learning about it. Ancient India was completely ignored during my k-12 education and I only took a couple classes in college that touched upon it. The Aryans introduced iron, horses, and chariots to India but where did they get the iron? They were still basically nomadic, how did they forge it? What advantages does iron or metal working in general give? Why was it easier to forge copper/bronze than iron?
iron is much harder than bronze, and keeps an edge longer.
ancient bronze age armies would have to have smiths with them to beat the weapons and armour back into shape after some battles. where, with iron, a sword just has to be re sharpened.
as to the nomad thing, did they travel to sites that they knew had certain resources?
iron working gives many advantages over copper or bronze. though copper and bronze are easier to produce, they are not as hardy as iron, also, copper is very rare and is valued because of that....for instance, the builders of the pyramids, who used copper tools, had to hand them to officials after a days work, so that they could be weighed, to ensure the builders weren't chipping bits of copper off for themselves.