Iron Age

Discovery of iron and steel, and the ability to forge them. Equivalent to Celtic and Viking societies.
If you want to play a "no-magic" game, especially a gritty realism one, Iron Age technology will suit that style well.

Materials

cotton textiles, iron and steel tools and weapons, parchment

Armor

ring mail, scale mail, studded leather

Weapons

longbow, longsword

Warfare

cataphracts, catapults, hill forts

Social Organization

city-states

General

arch, dome, locks, loom, screw, water wheel