"Their wagons have bypassed your inaccessible site."

[Wyfirion the Battle Gnome]

I don't understand why the wagons have to be so difficult. My fortress is in a forest, I have no coal or flux stone, and so I have to trade for flux. I absolutely need wagons to the accompany caravans. I have made a stone pathway from my entrance to the map border. I have cut a 3 square wide path around the map and check it regularly for trees. This game needs a way to check if there is appropriate caravan pathing. I'm tired of pulling my hair out every time a caravan comes and hits me with another message of wagons not having an accessible site.
I guess I'm going to try and litter the surface with stockpiles so that saplings hopefully don't grow and block pathing anymore.

[Dagmar]

There was a way to do that previously, but a path around the edge of the map isn't going to help unless that's where you put the Trade Depot.

Pick some non-economic stone and pave a road three tiles wide to the edge of the map.

[amade]

Can you post screenshots of the entire path to the depot?

[Fincki]

When you have a 3 wide path from the depot to the edge of the map the wagons will spawn so that they can reach that path, there is no need to have a path around the map. You can even control where the wagons will spawn, when all other ways are blocked the wagons spawn right at your path.

btw it's also a good idea to have that path mostly underground.

[HueSatLight]

do you have traps at the entrance to your fort or anywhere on the 3 tile wide path from the entrance to the trade depot?

I second the "mostly underground" part. I put my ramp about 4 tiles in from the edge, with a hunting dog near the entrance, so I am ready with the army or closing a bridge in time.

To have both a wagon route and traps, make the wagon route more winding, and put a direct route with traps. It doesn't have to be winding by a lot, a curve with traps along the inside wall of a 4 wide tunnel will hit most invaders, but some mill around sometimes.

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but make the trap section longer.

[MoonClipper]

It sounds like you're expecting the traders to leave their wagon at the map edge - that isn't the case. The wagon needs to go all the way to the depot. Paving the entire map edge is a waste of time. If you're low on materials you can make dirt roads instead but paved roads are best.

Like the others have said, the common method is to pave from the edge to a tunnel that then goes down to the stone layer and into the fort or to the forts entrance from there.

[Fincki]

Depots are fun. Some advanced strategy is to put the depot in a kind of of airlock. Traders will always path to your depot while enemies try to path to your fortress.
So having an open path to your depot but blocking the access to the fort with some draw bridge will only let traders path to the depot. Once they traders have arrived at the depot close the access path and open the bridge to the fort. No enemy will care of this part of your fort.