As the cosmic alignments vanished, trolls and elven people reunited and traveled together toward the astral plains. They've had to pass through several ancient battlefields, and have learned a great deal of hidden lore about each one, thanks to the trolls' necromantic abilities, with the elves acting in their traditional role as mediators and go-betweens. This includes the sites of treasure caches, where long-dead soldiers had stashed the plunder of their campaigns, never to dig it up again and reclaim it.
The unlikely alliance between ancient enemies was formed through wide-scale acts of reparations and forgiveness by both sides. After long travel on the astral road, the two peoples have intermingled more than any could have expected: trolls are called "auntie" and "uncle" by elf children. The Council of Longhouses has returned centuries of stolen bones and grave goods to the Muckmoot. It is not uncommon to see families opening their tents to members of the other species.
In the face of the Sunset of the World, it is reason to hope.
Word of their abilities has spread, so that desperate travelers will come from far and wide bearing the remains of their restless ancestors. They hope that someone in the caravan can make contact with these ghosts in order to resolve unfinished business, centuries-old disputes, feuds, etc. This has brought the caravan a great deal of unexpected wealth, along with increased scrutiny. Gifts of food and drink are consumed quickly, but the material gifts are slowing the caravan down and attracting the attention of local bandits.
Troll and elf wagons started off with extremely distinct looks-- the trolls tending mushroom houses on the backs of giant spiders, with spores from the fungi fruiting inside the spider's brains and allowing for some rudimentary control by trained Troll wagoneers.
Elf wagons look like wooden towers with colorful tents hanging off of them, like mountain climbers on a cliff-face. They are pulled by creatures that look like a cross between zebra and goat. They also had these delicate wooden Strandbeest things, only load-bearing and requiring 1-4 elves to steer, working in shifts.
Hybrid designs are starting to merge, intact spiders yoked to strandbeests, mushroom domes clinging to moving wooden slats.
These all surround the caravan's main wagon, a 16-wheeled longhouse.
The opening of the ancestral gates
To travel to the astral plains elves and trolls had to unite their efforts to open their ancestral astral gates. The trolls performed an exhausting ritual to open the gate (and awaken the gatekeepers in the process). This effort left most of the trolls unconscious from the effort. The elves were then left with the task of negotiating for passage with the awakened gatekeepers, citing ancient precedent and even introducing new arguments. The gatekeepers were forced to concede, but at a cost. Four living sacrifices were required for passage. This was non-negotiable...
The gatekeepers look like elven-trolls or maybe trollish-elves as once both people were one.
Their common ancestors are now extinct as a civilization. Only certain individuals held in ritual stasis (like the gatekeepers) still exist on the material plane. There are rumored to be a few scattered diaspora communities where they do their best to recreate their civilization at its imagined height, but they function more like a cargo cult than anything. There are also "orphans" making their way as astral vagabonds, but most of them have no idea of their origins. In any case, they can barely viably reproduce. Some of their number are convinced that this is all for the best, and that their essence lives on in their "seed races" while others refuse to accept the situation and seek for some other means to perpetuate themselves in defiance of time and biology.
A child of the two races has been produced, and named Root. They are expected to become the Messiah of a new race, all actions are watched closely and seen as auguries, Troll shaman read the stools, Elf seers divine the flutter of eyelids. Others may follow, united as the caravan is on the path what will occur when the destination is reached, Root may become conflicted.