Currency

Thinking about it for only a moment gave Ed his answer. Of course, they needed currency!

'Currency makes everything simple' Money was essential for any civilization. It was a tell-tale sign of advancement and evolution.

Money had two simple purposes. One was the obvious one, to pay for stuff. The second was to simplify the paying for stuff. Currency was oftentimes easier to transport than boar meat as a random example and was also much easier to assess its value.

The boar meat would always be relative to the person you were trading with. Maybe they don't want to accept boar meat then what do you do? Starve? Well, maybe not since you have boar meat but with the money scenario, the person wouldn't decline. Money was always useful.

That was because it could be used to buy everything. Even if the orc were to accept your boar meat somebody else might not take it and in that case, they'd have something that could rot before they had the chance to finish it.