Buddhism pretty sure that s the answer?
Artisans organized medieval crafting guilds for a very good reason - it was mostly because it benefited themselves. They found out that if they stuck together and helped each other out in certain times, it was beneficial for them as they could earn more and have less "stress" with not having jobs or enough equimpent or knowledge.
Fairly sure the answer is: It allowed people to buy and sell goods in a wider market.
Think about it: without coins, people had to barter with mostly short-term goods, but coins held value over time and most people would accept it as payment. However, if you had to use, say, carrots, the guy you're trying to buy lettuce from may not need/want carrots, but he can use those coins to buy what he DOES need.
Hope I helped!
Answer:
Paleolithic Age or Old Stone Age
