all tribes hunt, gather plants, raise reindeer and horses, and make things. but some are better or more renown.

mammoth tribe: their part of the valley is more hilly and arroyo/wash out canyons. the best blacksmiths and flint knappers of the tribes, and every year mammoth herds come through. they can feed on mammoth meat year round, use the hides for everything, and make weapons and tools from the ivory and bones. funny enough not very artistic. they are bigger and stronger than the other tribes, including the omegas. there are stories of mammoth tribe omegas being bigger than alphas of the other tribes.

rabbit tribe: small and light. they are shorter and quicker of foot, making their way easily through the heavy forests of their corner. they are incredible experts of food and medicine plants. often said that a rabbit tribe member will forget more about medicinal properties and food uses of plants than mammoth or reindeer tribes people learn. if your ever injured you hope you are near the rabbit tribe.

Reindeer tribe: the herdsmen of the valley. the are lanky and tall, and can run faster than the other tribes. they take care of the biggest herds of reindeer and horses. instead of small family herds of less than a handful, they combine their reindeer herds into clan communal herds of tens and dozens. they are the more artistic people. they will decorate their clothing and weapons and tents the most. often favorite 'pets' get pigment on their hides and carvings on their antlers. young reindeer tribes people get a reindeer calf or two or three to take care of as a kind of proving. they live on plains with big rivers dissecting them.

Wolf tribe: the hunters and warrior. they are stocky but can still run reasonably well with good endurance to tire out prey. Wolf members are as comfortable hunting from horse as well as on foot. keen eyes are great for spotting prey or amiss details. all four tribes 'war' with each other, using raiding parties, forays to capture omegas and sometimes skirmishes to gain territory but the wolf tribe does this the most. they spend many hours even in adult hood training and sparring. their corner of the valley is a wild mix of woods, rivers and meadows.

(authors note: tribe traits are based on body type. your characters can be whatever race or whatever they want)

relations:

tribes are split into little settlements of clans, 2-5 family groups led by a matriarch omega. clans and villages are named after locations. each tribe has 3 clans.

the rabbits and mammoths are often hostile. their border territories are just as good for medicinal plants as well as flint obsidian and iron.

rabbit and wolf tribes are actually nicer to each other somewhat. they trade regularly, using each other to get goods from their rivals as well as each other. wolves trade meats furs and bones for medicinal plants and others to supplement their flavors. its common for wolf alphas to have a thing for rabbit omegas.

wolf and reindeer tribes are rivals. reindeer herdspeople want as much grassland for their reindeer and horses. wolves often venture into reindeer territory for the large grass eating animals like irish elk and bison and sometimes even tamed reindeer. in times of conflict carved antlers are taken like prizes from butchered reindeer. 

mammoth and reindeer are more sociable but not quite. they trade materials with each other. mammoth tribe rifles and spears are worth many reindeer hides. mammoth tribespeople are hilariously confused by the decorations reindeer tribes people put on their weapons.

and of course tribal feuds, clan feuds and even individual families dislike each other.