So im playing a game where i have a very wide empire, horizontally that is. The starting landmass i was on was very wide, so i settled across the top, i usually try to build a trading hub city where all trade routes go out from with the best routes, to do this i usually make smaller routers over the course of the game to setup trade posts in all my cities and in key city states.

If you dont know, land routes can travel 15 tiles, while sea routes can travel 30, each of these distances then get refreshed for each trade post the come across.

What i cant understand however, is why my trade routes are so limited from my city Adwa, as seen from the first image, i cant even reach my capital, EVEN THOUGH there are trape posts in both Vatican City and Kandy, each of which would provide more than enough travel for my traders.

But then if you look at my city Axum, it can easily span my entire empire, hitting all my cities, my capital, Vatican City, Kandy and even Adwa and still also go into the sea to multiple other locations.

How? How is this happening? Why can seemingly most of my cities reach across my empire, except the one city that i actually want to reach all the wy around?

If you wonder why i want to send everything from Adwa, its because i built the Great Zimbabwe there with quite a few bonus ressources which synergises well with Etheopia.

Please, if anyone can explain this, i am so lost...

How do trade routes ACTUALLY work?