[inglor_cz]

Metal is too precious to be just abandoned. Metal is usually recycled, even in our civilization.

Whatever metal objects from ancient civilizations we know, are either grave goods (swords of warriors etc.), or were found in shipwrecks etc., or were found in destroyed settlements, plus a few accidentally lost (fell into a well etc.). But most metal objects get recycled.

[EdwardDiego]

That's a very good point.