Sheep
Sheep descend from ancient mouflon that humans domesticated thousands of years ago. The feral sheep of the Fifth World descend from domesticated sheep, but have evolved not to produce as much fleece as domesticated sheep currently do, so they no longer require regular shearing. They have also regained their ancestors' colorful coats (so fleece no longer comes just in white) and great curved horns.
#Human relations
People in the parts of the Fifth World where sheep still roam will occasionally hunt them for meat, leather, and wool. They rarely use wool for clothes, due to the Fifth World's heat, but will frequently make bedding and rugs from it.
Communities that live closely with sheep predominate around the poles, where it remains at least occasionally cool enough to sometimes warrant the wearing of wool. Given the long tradition of shepherding in Australia and New Zealand, and those places' disproportionate role in settling Antarctica, combined with Antarctica's grassy mountains and long winters, many communities specializing in relationship with sheep live there.
As the Arctic and Antarctic lands lay under glaciers until fairly recently, these newly-emerged lands grew little more than moss and grass during the early years of settlement. Raising sheep became an important way for early settlers to produce food. As time went on, settlers became hunter-gatherers and the sheep began to go feral, no longer in a relationship of domination but the normal relationship of predator and prey.
Thus, one most commonly finds shepherding communities in Greenland, the North American arctic, parts of the Asian arctic, but one can also find them anyplace rocky and marginal enough that grassland predominates over the more typical jungle (most often at high elevations).
#Specialization
A community specializing in relationship with sheep will live as nomadic hunter-gatherers, following the semi-feral sheep flocks as they roam across mountains and hills. Humans will gather wool from where sheep shed it. Because they rely mostly on shed wool, they may take up weaving only seasonally, to coincide with the time of year the local sheep herds shed. Thus, they may have a weaving camp further up in the mountains than they usually live, where sheep like to roam. They may live in collapsible tents made of animal skin (larger animals than sheep).
Some flocks of sheep find themselves protected by packs of feral dogs, descended from sheepdogs of the Fourth World, who still remember their ancient responsibility. Human communities specializing in relationship with sheep will often have to ask permission to hunt sheep both from the sheep themselves and from the feral dogs that protect them. These dogs remember the betrayal of human domestication, and remain wary of humans. Human communities must therefore take great care in making amends for their ancestors' misdeeds.
Communities specializing in relationship with sheep will quickly become known for their skill at weaving, producing bedding, rugs, bags, woven bracelets and necklaces, and occasionally (in cooler areas) clothing that they may trade with neighboring communities. These communities will by necessity also have a good knowledge of local dyes so they can make their woven products colorful. Their talent for the visual arts likely doesn't end at weaving; those dyes can also become paint to decorate caves, old concrete walls, bodies, and ceramics.
Sheep have long played an important role in the traditions of the Diné people (also known as Navajo), who continue to live in the (now warmer and wetter) American west. The Diné have historically raised a breed called Churro sheep -- smaller and with longer, softer fleece than most domesticated sheep. Despite late Fourth World attempts by colonizers to wipe out both the Churro sheep and the Diné who care for them, they continue this tradition into the Fifth World, maintaining their responsibility to the sacred sheep and weaving widely admired blankets and rugs from their lustrous fleece. A community specializing in relationship with sheep may trace its descent from the Diné, or have such close contact with them that the Diné inspired them to take up the shepherding life.