Mine is just weird. Yeah, in Civilization you're used to things like Venice is in South America or seeing Helicopters fight Pikemen. But, I don't know if this is common in Civilization 5 ( I am still finishing my first game), I, for whatever inane reason, got insane amount of horse resources. Ok, the number itself is not insane, but still, it's reaching 100000 now. And so, I don't need to worry about any kind of trades. I just offer horses and get whatever I want. That led to me to not worry about money. I just focused on food and production. I got the money from trades. 
Towards the end, I just decided to try to accomplished as much of goals as possible. Since I was a bit behind in the Total Domination, I just bought all the cities of a civilization with horses and then conquer the capital. And this in 2000 something. Just weird.
 
Is this horse situation common? I was playing on normal, or whatever normal is.

it's a bug where every turn the keep cancelling/ending the trade but still get the horses back. I believe the next patch will resolve the issue.

Congratulations, you are Rohan! Land of the horse!

I would kind of prefer if superseded resources just disappeared once you've advanced to the point of never needing them. Yeah they're good for trading with less advanced civs but mostly you just look up and go "oh, I have 150 horses and I can't really fo a thing with them".

" Congratulations, you are Rohan! Land of the horse! "

i had like 50 iron right when i didn't need them.

There was also a time that I wanted coal from another CIVs so I trade that with horses, naturally, but, the coal never appeared in my resources. Why was that?