Later Kushans. Kidarite Succession. After 400 AD. AV 25 MM gold Stater. 7.79Grams, King standing left, sacrificing at altar; trident standard behind.
The person I bought it from had 360AD as the time, but close enough.
It's a lovely gold coin. Heavy and satisfying to hold.
It looks to be closer to electrum than a gold and copper alloy. Wikipedia can give you more info:
https://en.wikipedia.org/wiki/Kushan_coinage