Hallo Callicles!
To my opinion, we should
search your coin in the Mongol Empire.
The high reversed "S" to end a word with, is not how an Arab writes. Some Mongols did, I think. Most likely the text on the
obverse is not Arabic, but another language, most likely Persian. The script on the
reverse is different. It is the "
kalima shahada" in copied Arabic. I believe I can recognise the word "rasul" and some x-like "al" or "la" above.
I can be wrong, but I would look out for a
Khan, who was ardent muslim enough to put the
kalima shahada on the
reverse of
his coins
.