Finish an Era with 1200 Prosperity
If we approach this Development with a logical head, 1200 prosperity breaks down neatly into either 6 villages with 200 each (extremely easy) or 4 each sporting 300 (also very far from impossible).
With this knowledge in mind, proceed to build. Put a focus on diversity, you’ll want to spread ambassadors around your giants with a focus on opening up their locked aspects so that you can easily apply required aspects to resources.
continue to cover the world in resources in this manner, answering village Project requests and focusing on logical synthesis (Agate next to Agate, a diverse Ocean make up, Pear Trees flanked by other plants etc.) and 1200 prosperity should come easily.