The Dark Age is where your relationship with the battlefield is set. Your Town Center anchors the map, villagers fan out to gather Food and Wood, and every building you place is a bet about where the game is going.
Because resources are scarce, the Dark Age rewards restraint. A settlement that overbuilds economy gets punished by the first raid; one that overbuilds military falls behind and enters the next era poor. Learning to read that tension — and to scout before committing — is the core Dark Age skill.
Strategically, expect to make three kinds of decisions: where villagers work, when to add your first military building, and how early to bank resources toward advancing your age. There are no shortcuts. The empires that dominate the Futuristic Age are usually the ones that survived the Dark Age with a plan.