I was searching for an alternative to reddit and the first result was a subreddit dedicated to such alternatives. Then I just clicked on all the links until I found a site that doesn't suck too much. Just kidding, I'm liking it here. The user interface was definitely a bit confusing at first, but only because it was different from any other site I'd seen. Now that I've gotten used to it, I think it's actually very well designed.
https://hubski.com/tag?id=history&time=all That, or follow somebody who posts about history.
How do I discover new communities? For example, I typically follow /r/Eatcheapandhealthy, /r/trollxchromosomes, /r/femalefashionadvice, etc. Is there a list of "subs" or whatever their equivalent is here?
At this point, there's no separate "communities" like Reddit. If you like a subject, you follow a tag and if you like what a person posts, you follow them.