They're Barbie! I had them second hand when I was a little boy and didn't know what brand they belonged to until last year when I saw a Tumblr post about them. They come both in fantasy and "normal horse" colors.
Do you know what line/set they’re from?
After a quick google search I found this:
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loginHere's the back of the box
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loginHere is a different set of horses in the "real" colors I mentioned before
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loginOn the boxes they have the name of the set they're in followed by "mini collection". Based on what's on the back of the box I'm guessing that the "mini collection" was only horses. It also seems that besides being just toys these are also collectibles for Barbie herself, hence the "Barbie loves to collect them." part. We need someone who actually knows anything about Barbie to confirm this though since I don't.