The creatures depicted on your charm are Shang Dynasty Dragons, that were used throughout history as decorative motifs on jade & ritual bronzes. Original Shang Dynasty art objects are over 3,000 years old, however, your charm is not ancient but it might have a little age. Your charm is known as a Bi Disc, one of the oldest Chinese talismans usually made from jade. The photo below is a jade talisman from the Ming Dynasty that I sold at auction, & it also has Shang style dragons decorating it to form a Yang-Yin design like your bronze charm .
