Finish an era with a Village which has 1250 Prosperity and no Warmarks
This Development isn’t too tricky. All you’re trying to do is raise a village without letting it go to war. So, as usual, start by moving around the world 'farming' ambassadors so that you’ll be able to answer a village’s Great Project Upgrade requests later in the game.
This development really is a simple ask of doing this and then growing a village slowly, or with appropriate danger. Remember that danger (produced by Animals, predominantly those upgraded through the Forest Giant’s Hunt aspect or the Swamp Giant’s Predator Aspect) is a balancing act, you want it in the middle.
With this focus on danger in mind it’s a grand idea to focus your Rock Giant Ambassador choice on his requirements for Iron. Iron is a great way to capitalise on danger, generating a huge pool of resources. Not only does this move you closer to your goal, but more resources will facilitate more danger. Danger which will, in turn, generate more resources through iron.
It’s a beautiful circle.