The Gathering

You should see it, lad, the Gathering is an incredible time, I tell you hwat.
So many ships ancored so close to each other that they form a city of decks in the middle of the ocean. You'd need another Great War to see that many ships in any other context, I promise.

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The Gathering is a tradition of the Andalsti people, practiced in several different variations depending on what subset of the nomadic people in question.
At it's core, it's a tradition that is meant to be a cultural exchange of sorts for the Andalsti, where their many disparate groups come back together for a short time, trading goods, stories, and at times; individuals in the form of marriages and friendships.
For the Sea Andalsti, it takes place every ten years, to account for the large distances that convoys have to cross. The scale of the festival is much greater than the other subgroups, essentially becoming a month long floating festival. 
For the River Andalsti, It's much more frequent but more self contained as the individual clans and families within the same general river system come together, but the expectation is much smaller. They may all converge on a single down, partying there for some time before dispersing back to their usual haunts upon the river.
The Lake Andalsti don't gather as often as the other groups, considering that there isn't often more than one community of the Andalsti within a singular lake system. They do, however, often invite the towns that they visit into their own festivities whenever they enter into towns to resupply.

Execution

The specifics of the Gathering are non-standard, changing between individual instances and regions in equal measure. 
Sometimes they are more strucutred, being akin to a county fair; with games and festivities. Othertimes, it's more like a family gathering with clans simply overlapping in the same place, drink and food flowing as long as hospitality allowed.

Related Ethnicities

• Andalsti