Another question related to that fantasy novel I’m gonna finish one of these years. A character needs to move the biggest load of cargo he can a couple of hundred miles without help. What’s the largest team and wagon that one experienced drover can reasonably manage by himself?
The driving *per se * is always handled by a single person, and I’ve seen teams up to 10 horses (pyramid hitch for an exhibition). Keep in mind that your drover won’t just be driving - he’ll have to get them harnessed and put to the vehicle (not to mention fed, etc.) every day that he’s travelling.
This is easier and safer with an assistant. In a stable, a drover might have the advantage of an overhead tie system to safely hold the horses while this is going on. Since you specify “without help,” this won’t be an option in your story. Realistically, a single person can handle a couple of horses and might be able to handle up to four horses if they (the drover and the horses) are exceptionally calm, experienced, and willing to disregard safety for the sake of the story.
As cwthree said, driving the team isn’t the whole story. When I saw the Budweiser Clydesdales here a couple of years ago, I think they had 6 handlers to get 8 horses ready for the show.
<nitpick> A drover herds animals, a wagon is driven by a driver, or teamster.
Her’s Wiki’s take on large wagons and teams: Twenty-mule team - Wikipedia
I can’t find the cite, but I recently read an interesting factoid about the 20 mule team. The mules towed the wagons via a chain which of course pulled completely straight. This is problematic when rounding a curve as the middle mules would either be squished against the side of the mountain or pushed off the side of the cliff. Thus, the middle mules were specifically trained to be “jumpers” and the would jump over the pulling chain when rounding a tight curve.
“Swinging the team around a curve in a mountain pass tested both driver and team: one mistake could spell death for all. As the team started around a sharp curve, the chain tended to be pulled into a straight line between the lead mules and the wagon. To keep the chain going around the curve and not pull the team straight over the edge, some of the mules were ordered to leap the chain and pull at an angle away from the curve. These mules — the pointers, sixes and eights — would step along sideways until the corner had been turned. Swinging a curve successfully was an awesome demonstration of training and teamwork.”
Ok, so a freight wagon pulled by four very large and strong draft horses chosen for their docility and easy handling. What does that translate to in terms of load?
Well, the USA pulling record is 4650 pounds (10,230 kg.). Now that is in a pulling contest, so it’s just a stoneboat pulled for a short distance, or a measured pull against a dynamometer, thus would be different than a typical wagon load to be pulled all day.
In logging, a team can commonly pull a skid (non-wheeled) of 3,000 pounds (6,600 kg) out of a forest – typically, this is not more than 1/3 of a mile (1350m).
Draft horse wagons typically came with a load capacity of 2000 pounds (4400 kg) for a small one, going up to 3000 pounds (6600 kg) for a typical wagon. (That is the load capacity; the wagon itself adds weight to that load.) Loads would be adjusted for the length of travel (an overland freight load between cities vs. a delivery load within a city) and for road conditions (an overland route over rutted, muddy ground vs. a delivery route over cobblestone or other paved streets).
And “chosen for their docility and easy handling” – that is characteristic of all the draft breeds. You don’t have to choose for this – that’s what they were designed for. That’s why they are considered cold-blood horses.
You need to check your conversions t-bonham, 3000 pounds = 1300kg and 1/3 mile = 536 metres.
I would have thought that this would be the biggest variable. If our hypothetical character is moving stuff cross-country or along a narrow forest trail, he’s might struggle to move more than a couple of hundred kilos in saddlebags or packs. If he’s going along something like a well-maintained Roman road, several tonnes is feasible.
Maximum horse-drawn cargo-shifting capacity is probably going to be via a canal boat - according to this link these allowed capacities of up to 50 tonnes of freight per horse.
Another question - will the hypothetical driver and team be traveling through areas with abundant water sources and grazing areas? If not, you’ll have to allocate some of the cargo space to feed and water for the horses. Figure anywhere from 5 to 20 gallons of water per horse per day, depending on weather and how much the horses sweat.
Sorry about the side track here, but, if the last two animals were the wheelers and had to be horses because they had to be ridden, why did they have to be ridden? 'nother words, why are the wheelers important?

Another question - will the hypothetical driver and team be traveling through areas with abundant water sources and grazing areas? If not, you’ll have to allocate some of the cargo space to feed and water for the horses. Figure anywhere from 5 to 20 gallons of water per horse per day, depending on weather and how much the horses sweat.
He’s going to start out from a medium-size town where horses and a wagon can be had, travel through farm country, then grassland, then forest, then end up in the foothills of a mountain range. Then back again with the wagon loaded.