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 due to their thick, curled coats, they can only live comfortably close to the poles, and even there, preferably in mountainous regions.
#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, but will frequently make bedding and rugs from it.
#Specialization
A community specializing in relationship with sheep likely lives close to one of the poles, where it remains at least sometimes cool enough to occasionally 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, most communities specializing in relationship with sheep live there.
Such communities live as nomads, following the semi-feral herds of sheep as they roam across mountains and hills. As Antarctica lay under glaciers until fairly recently, the newly-emerged continent 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 nomads and the sheep began to go feral, no longer in a relationship of domination but the normal relationship of predator and prey. Or almost normal - humans will still shear willing sheep, and the sheep who accept this feel grateful for the cool. Though feral sheep no longer grow such long coats as their domesticated ancestors, freedom from their wool coats still comes as a relief in the warmer climate.
Sheep also play an important role in the traditions of the Dine people, who continue to live in the (now warmer and wetter) American Southwest.