Gold is big business.
Nowhere is this more true than in Age of Empires II: Definitive Edition. Gold is necessary for lots of deadly units, interesting upgrades and to buy other important resources. Hence why you’ll need a lot of it.
One way to get gold is to use trade carts, by sending these units to other market places you can gain gold quite effectively.
To do so, all you need is to reach the second age (the feudal age) and build a market. From there, you can build trade carts.
Once your trade cart is built, all you have to do is take it to another players’ market and the trade cart will go between your market and theirs and generate gold every time.
Make sure that the other nation is either neutral or allied to you: you can change your stance in the diplomacy menu (the AI will often go neutral with you if you do the same and require tribute to become allied). If you are listed as their enemy, they will attack any unit of yours – including your trade carts.
The more distance between the two marketplaces, the more gold will be generated, but the most efficient thing to do is to make sure the route between the two market places is clear and that your trade carts won’t have to keep turning and battling with other units and buildings to get to their destination.