Here is an excerpt from the World Book design notes on Caravans!
Men, Beasts, and Wagons
The largest caravans grant livelihood to hundreds of souls, each of whom has a particular task in its operation; there are no loafers on the wild roads. Those who cannot contribute are left behind, that is the code of the rolling cities.
In the broadest terms, a caravans personnel divide into merchants, guards, teamsters, followers, and cargo. Merchants include traders, brokers, financiers, and interested agents. Guards include outriders on thakal or faster swafa mounts, wagon riders, and scouts. Teamsters include wagon masters, beast masters, drivers, artisans and all manner of animal caretakers. Followers include cooks and personal servants, camp girls, dancers and entertainers, unemployed family members, and refugees of all stripe. Cargo are slaves, plain and simple; while any number of caravan services may be filled by slave labor, they are primarily trusted free men.
Often the caravan itself is the destination. When stopped on a frontier it becomes a bustling marketplace. Merchants set themselves up in tents to receive local traders and strike deals, taking on new cargos while dispensing objects they have brought with them. Stalls are opened and cook-fires lit. Idle caravan workers arrange games and sporting events and otherwise relieve themselves of their pay in squalid, unseemly activities.
The caravan relies upon its beasts. Probably half its cargo is hauled by thakal, either in enormous pack trains or in smaller carts suitable to their size; thakal do not work well in teams, but can be beaten into cooperation if necessary. Thakal masters generally walk alongside their animals, whipping them to greater effort or to get their attention to take a different track than the one preceding them.
The enormous cargo wagons are hauled by the dangerous trisaur, three-legged dragon kin found in the deep wastelands. They cannot be domesticated, so replacements must be captured, a dangerous process that involves drugging a wild beast into passivity with enormous cubit-long darts; unskilled slaves are expended in this process. Deaths are expected when securing a new trisaur and more when breaking it for use. They are never fully broken, though, and often turn on their drivers viciously; trisaur drivers are well paid, and only the toughest can make a career of it. A single trisaur is harnessed at its sides so it can bring it single, powerful hind leg to use pulling its load.
Elephants and colossadants are also common in caravans, even those far from those animals’ native lands around the equatorial grasslands and forests. Difficult to harness, these are fixed instead with howdahs or enormous nets stuffed full with crates, amphora, and boxes.
Elephants and colossadants tolerate each other well, but hate the smell of thakal. Handlers are careful to keep the thakal downwind from them whenever possible. Disturbed elephants and colossadants are far more difficult to control, and may in fact stampede if subjected to thakal smell for too long. The dimwitted thakal, for their part, are indifferent to the other beasts around them.
A caravan’s many animals leave behind a trail of excrement that, in turn, attracts a variety of carrion. Scavenging creatures follow in the entourage’s wake, drawing a variety of hunting carnivores. The normally silent wastelands teem with life along the return trail of a large caravan.
Simple thakal carts are commonly made of wooden frames with treated leathers using only a sparing amount of metal for axels and hitches. One can normally carry 6 to 8 blocks of weight, normally roped down to keep the load in place over the difficult path.
Elephants an colossadants cannot be harnessed, but carry enormous loads lashed to their broad backs. Some carry howdahs fitted to carry passengers or freight.
Of the large trisaur-drawn wagons, the single-chamber and three-chamber ‘mahuuth’ wagons are most common, as well as the lavish ‘shavinant’ rolling palace.
A single-chamber mahuuth hauls massive raw materials in heavily reinforced wagon fashioned from wood and reinforced with dragon and trisaur bones, as much as 40 blocks of material at a time (or roughly 10 tons). The top is open so the entire wagon can be tipped over for rapid unloading; slaves general load the single compartment from a ramp or other specially prepared place that can overhang its gaping maw. The interior lip has prepared locations for two archers at each corner who enjoy the protection of reinforced leather shields. The entire structure rolls on two enormous wooden axels and four wheels that must be often repaired or replaced.
The three-chamber mahuuth is similarly built and protected, but the roof is covered to protect cargo from scavengers, birds, and occasional bad weather. Separate ramps and entrances are built in for access to the front, center, and rear compartments. Three distinct cargoes can be hauled without them mixing along the journey.
A shavinant is a boastful luxury, reserved for the richest merchants and dignitaries. Its many cushioned compartments serve one purpose: the conspicuous pampering of its owner and his guests. Kitchens prepare fine meals served in an audience chamber large enough for elaborate entertainments even while on the move. It smells of spices and fine oils. Guards grace its many-bannered exterior battlements, slaves walk behind in chains. None approach who are not first invited; at rest a perimeter of pre-fashioned stockades is quickly erected and manned, keeping the curious at a safe distance.
Among the caravans, none get by without carrying their own weight. Slaves must carry heavy packs, baskets, or loads across their shoulders as the plod along in chains, spurred to greater effort by whips beneath the hot sun.
Caravans draw all manner of undesired followers. Anyone moving along behind it who has no direct employment is tolerated but generally not afforded any special protection from the guards nor allowed to directly participate in its profits upon conclusion of the journey. Many wives and families travel along so, as do shylocks, brewers of every sort of liquor, gamblers, women of ill repute, and all manner of unsavory characters. The moving caravan hosts every vice.
In addition to human followers, the rich leavings behind a caravan make them the new ‘rivers of life,’ especially in the most desolate regions. Offal and dung attract carrion and scavengers, squawking birds, sand worms, and all the filth and disease that go along with them. Shambling, desperate refugees live along these routes, as well, foraging for the scraps cast off along the roadside, then preying upon each other when those meager resources are picked clean. Bandits, in turn, prey upon the refugees in a perpetual circle of anguish.