Prax is the more fertile part of the Wastelands, although to outsiders even Prax is pretty inhospitable. There are stretches of scrubland in the Wastes that can support herds, and there are herds of Praxian beasts, wild and domestic in the Wastes.
Prax can only support so much livestock and so the weaker tribes and bands get forced out of Prax into the Wastes. They cross the Vultures Country into the Wastelands and find a vacant oasis. Sometimes they must wander deep into the Wastes until they find an unclaimed oasis or scrubland – or one with claimants weak enough they can displace them.
Life in the Wastes is harder than in Prax for both men and their herds. There is little trade, and many dangerous spirits. Those out in the Wastes must be self-sufficient. The Praxians consider life in the Wastes toughens men, makes them lean and hard. And when they are lean and hungry enough, they try to force their way back into Prax.
This is the great jostling of tribes, partial observed by outsiders. When the Praxians were defeated at Moonbroth in 1610, the Bison and Impala were forced into the Wastes, and replaced by the Sable Riders. When the Lunars were defeated by the White Bull at Moonbroth in 1624, the Bison and Impala returned and the Sables forced into the Wastes.
However, the White Bull offers another path – with Jaldon Goldentooth he offers the chance of war in Dragon Pass and even beyond. For many this is far preferable to the Wastelands. Dragon Pass is a fat and rich land where it is easy to feed herds. Peloria is legendary for its riches – a vast grassland with water year round! For many Praxians, this is an opportunity out of legend.
I imagine the movement of herds throughout the Wastes ends up looking like Brownian motion as herds deplete the fodder in an area and move to another. There are areas that all the herds try to avoid – the Copper Sands, the Tunnelled Hills, the Devil’s Marsh, etc. But around these areas, herds graze and then leave seeking new fodder.
The Praxians have invaded/colonized Peloria in the past. We all know about the Sable People of the Hungry Plateau, but also Sylilla and Vanch have had Praxian ruling dynasties. There were Praxians bands in what is now the West Reaches and Charg in the First Age as well.
A key component of Praxian culture is “winning” tribes are able to graze in Prax, where they have access to bronze working, luxury goods, better fodder, Eiritha’s presence, etc. This is done primarily through Sartarites – so there is a big Sartar/Praxian overlap in Prax. Tradetalk and Sartarite are significant secondary languages etc.
But meanwhile in the Wastes, the “loser” tribes get lean, hungry, and desperate. They seek allies, look for weakness, and take whatever opportunities they can to force their way back into Prax. If successful, the “losers” replace the “winners” and we have movement between Prax and the Wastes.
This just happened in 1624 – but rather than have the Sables all be forced into the Wastes, Argrath has made it clear he intends to lead them into Dragon Pass. This happens in 1627-1628, which gives Argrath a deep endless supply of veteran cavalry and magicians. The traditional Sartarite weakness with cavalry is reversed and the Lunar advantage is more than neutralised.
Now there are some 475,000 animal nomads in Prax AND the Wastes. Now that is both a big number, and also something that spreads out very thin over such a large territory. So the Wastes both seem empty and are a source of seemingly limitless nomads (from the point of view of outsiders).
Inside Prax, the nomads are influenced by the Sartarites not only through trade (which is significant), but also the presence of the cults of Humakt, Orlanth, Storm Bull, Yelmalio, etc. The trolls are also a significant influence as enemies and have overlap with the morokanth (a not insignificant number of morokanth are devoted to Zorak Zoran). The Paps are the home of Eiritha but also her mother is present there.
But in the Wastes, Waha is most important. He shows the nomads how to survive in that hostile environment. There is enough room for Storm Bull (necessary to deal with the Chaos in the Wastes) and together they protect Eiritha (necessary for the herds). But there is not a lot of room for more.
The Praxians do interact with the Pentans, but normally it is quite negative. First horses really don’t do well in the Wastes. Second, they have an ancient mythological grudge with the Horse Barbarians.
After the Dragonkill War and the closing of Dragon Pass, the Animal Nomads entered into a period of comparative calm and growth. Their intertribal warfare continued, often disintegrated into inter-clan fighting in the Genertelan Wastes. Yet they prospered, relieved at last of the troublesome influence of the civilizations in Dragon Pass. Minor adventures in the Holy Country, Kralorela, and Teshnos were viewed with alarm from the inhabitants of those regions, but their retaliatory raids failed to do long-lasting damage to the Animal Nomads. It is probably fortunate for those regions that the ancient ancestral grudge against the Horse Barbarians of Pent was greater than their lust from the luxuries of civilization.
Cut off from other areas of expansion the nomads expanded northward into Pent. This was a gradual process of many generations, yet proved inexorable. Both the Animal Nomads and the Horse Barbarians have stories about the famous battle of No-Feet-on-the-Ground, where even the sun and storm took part so that the earth itself recoiled and withdrew from contact with the battle. Its date is uncertain, and the multitude of conflicting information makes a sensible recollection impossible. Regardless, the battle was a disaster of immense proportions for the Horse Barbarians. They were split into East and West divisions, and reeling into civilized lands in the north. Their arrival in Peloria was during the Lunar Third Wane.
The width and depth of the Zola Fel varies with the season. At its shallowest the River of Cradles is a meter deep and ten meters wide. At the crest of a flood it might be 400 meters wide and at least six meters deep, and be quite swift-flowing besides. It is normally a gentle river, slow-moving and without serious obstacles until above Pavis.
During Storm and Sea seasons the river is usually between three and four meters deep and from 100 to 200 meters wide, sometimes growing much larger during the floods, and, during years of drought, being less. The river drops down to only a meter or two in depth and twenty to a hundred meters wide during Fire season, and remains wadeable during late Fire season and early Earth season, when the rains begin to swell it again. It reaches a depth of two to three meters during late Dark season, and then increases up to the yearly height during Storm season. Depending on the season, there are plenty of fords across the River of Cradles.