The caravan baggage train is as good as ever a indication of the trust that the civ has in you, with good trading relationships and offering valuable items (artifacts notably have a lot of traction when offered or least a lot of value traded) the caravan trains will start to swell larger.
Just the same, civ trust is damaged by the caravans being misplaced or destroyed without applicable and believable cause like a invading army, especially when it comes to having a eyewitness escape that can testimony a caravan destruction to being more than a 'misunderstanding' of a hostile action, and in most other cases with neutral parties, the civ sending the caravan expects you to do your due work & protecting and sheltering the caravan/pack animals from weather and wild animals.
Goblins dont technically have any animals to pull their wagons, but once adequate pacified by demanding continous tribute from their remaining active sites they'll no longer be hostile potentially in theory opening up the window for further trade negotiations, but this compliance number-game often dries up as they'll terminate the arrangement after a period of time. For a breif period however, there will be peace, and a few offerings.
As far as I understand that just results in larger caravans for other civs (up to a limit that can be reached by just giving them big profits), and did contribute to getting saddled with a monarch before holdings were introduced: don't know if it still does factor in the monarch attraction process.
A set number of types of jobs (glassworking, gemcutting, metalworking) 200 dwarves & a substantial amount of exports will call any position labelled as [POSITION:MONARCH] to your fortress in the same process, even if they're a dark-fortress generated clown. They'll be accompanied by two expertly skilled weaponmasters, but other entities the monarch has a hand appointing will remain offsite.