Armament

The inhabitants of Westeros and Essos been using weapons made of iron and steel for at least the past six thousand years.

Materials
When the First Men migrated to Westeros twelve thousand years ago, they introduced weapons made of bronze (copper/tin alloy) to the continent. The copper mines of Slaver’s Bay were used to produce bronze weapons for the legions of the ancient Ghiscari Empire in Essos. The superior iron weapons of the Andals were a decisive factor in the success of the Andal invasion of Westeros six thousand years ago, sweeping aside the First Men who were equipped with weapon and armor made of weaker bronze. In time, the First Men in the North who had managed to repulse the Andals from their lands adopted many of their customs, such as their language, writing system, and knowledge of forging iron weapons.

In the present day, bronze weapons and armor are a relic, not seen on the battlefield, though some of the more sophisticated wildlings living Beyond the Wall in Westeros forge their own bronze weapons, much as their First Men ancestors did. While the wildlings lack the ability to forge iron weapons on their own, they frequently trade with smugglers for iron weapons (in exchange for furs, etc.), so iron weapons can be encountered in the possession of the Free Folk