First iron swords on mass scale

Hello!

This may be a trivial question but I have really tried to
find an answer - with no success.

I've always thought about Hittites as propagators of
metallurgy and first users of iron swords. However, this
turns out to be incorrect, as I've learned about the Sea
Peoples (Phrygians, Philistines?) who invaded the Hittite
Empire in the 13th century BC. Their iron swords gave them
an advantage over Hittite soldiers. And this exact period is
marked as the beginning of the Iron Age. At about the same
time, iron swords were used by Doric tribes invading Achaean
Greece from northwest. How did they get the iron swords if
they had no earlier contacts with Hittites (in contrast to
Achaeans, but they still used weapons made of bronze)?

So, my question is: When, where and by whom were the iron
swords used first time on a mass scale?

Michal