Is This Oriental A Coin Or A Medallion ?

It's definitely not a coin made by a government. It's probably made by a company in China. I see lots of these gold-plated coins selling for under $2 on ebay. Usually they depict the 12 animals of the Chinese zodiac. Not very rare, since these are mass produced, but good for a present, or display, I guess.

So it could be a coin, token, or medallion, whatever you want to call it, but it's not made by the government, it's made by a manufacturer. I think you could pick something like this up at a Chinese souvenir store.

I would keep it in it's packaging.
The coin is definitely gold plated.

It's really hard to find out who made this coin, there are millions of zodiac coin makers in China.

Brass lunar medal made by the Shanghai Mint. It says Shanghai Mint on the bottom, opposite the date (1999)
I would not open it.