I'm no expert on Civilization, in fact, I just started a few weeks a go, but I played it for many hours. I found that if you negotiate with other civilizations early on for Open Borders on your side only, you can get a decent amount of gold early on to set yourself up to become an economic giant. I guess the only negative things would be they can go through your place and discover other stuff more easily that helps them out, but open borders early on doesn't seem as big of a deal compared to when empires are giant.
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