How to get gold in kittens game

As per the wiki page on trading, there are currently seven races to trade with. The three you have are likely the Lizards, Sharks, and Griffins, all of which only require Year 20. The others' requirements are as follows:

• Nagas: 1500 culture
• Zebras: Own a trade ship
• Spiders: 100 trade ships, 125k max science
• Dragons: Nuclear Fission researched
• Leviathans: Black Pyramid researched

Also, note that while exploring is listed as costing 1000 Catpower, failed exploration only costs 100; if you're ever uncertain whether another race can be found, this reduced failure cost is intentional, to let you explore a few times to see if it works.

Gold is used in many buildings, the Tradepost and Temple being among them. It's also required for trading, so if you want to ever get specific resources faster, you're going to need gold. It's also used in many faith upgrades, and some workshop upgrades.

Any way you look at it, gold is very useful. You need it. Lots of it. Compared against the Amphitheater, though, it depends on what your current happiness level is at. The lower your happiness, the more I would weight getting them, as they give corresponding kitten efficiency bonuses, whereas gold is used to progress.