Answer: Babylonians in Mesopotamia
Explanation:
Byzantine Empire. They were Islamic too I believe.
The reason why it's valuable is because there is very little of it in the world I can't describe it because I've never really seen it but I do know that you can find it in the ground mostly in little flecks I know this isn't the exact answer but it's all I have.
Pros : It would allow people to buy now what they might not have money for immediately. If the borrowing is used to invest in generating income or building marketable skills (education) it could more than pay back what is owed.
Cons: The money must be paid back with interest. Borrowing may encourage people to buy more than they really can afford.
The Spanish Empire or the KIngdom of Spain or just Spain