A trade route connects the inn and another location, allowing the player to buy goods. To create a trade route a player needs to have enough influence in the given place. To gain influence in a city the player has to make sure that guests hailing from there will leave the inn satisfied. The blue gossips can be used to increase the influence.
Once the player has enough influence, they may choose the option Create New Trade Route.
The new window tells the player what resources are popular in the location. The player also chooses the way they want to pay for the creation of the trade route - either with green gossips or money.
Once a trade route is created, new locations appear on the map. Small locations - villages, houses, vineyards, etc. - become available to trade with. Major locations - towns, cities, capitals - appear on the map, but require new trade routes.
(For example - the player creates a trade route connecting the inn (green on the graphic) and Plouven (red). This in turn unlocks two major cities, one to the north, one to the east. The player cannot trade with those nor gain new objects/recipes and so on, until he creates a new trade route, connecting Plouven with a desired location. However, all the smaller locations along the trade-route-to-be are unlocked the moment they are discovered.)