You're right, I was just thinking within the frame of Pdan's answer. If the AR part of the UA has to be small because half or more of the community doesn't play with AR on in the first place, then it has no business being in an UA at all in my opinion. It should rather be designed like the mayan holkan of 4UC.
I'm not very knowledgeable regarding the Shoshone's culture and history but based on that reference (http://freebooks.uvu.edu/NURS3400/index.php/ch09-shoshone-culture.html, which seems credible albeit with strong Utah flavor
) here are some ideas:
- A mechanic echoing their strong animism ("The Shoshone people were greatly connected to their land. They respect the native plants and animals and appreciate the land in which they live on. They believe that every plant and animal as well as the land itself has a living spirit and that the plants, animals and people maintain a relationship.") : it could be a bonus for any one/two unimproved tiles within their territory (synergy with their land claiming ability).
- Increased war weariness for the attacker pillaging/occupying Shoshone's tiles ("The Shoshone tribes believed not that they owned the land, but that they were one with the land in which they inhabited. They have such a strong relationship with their land that any damage done to the land they inhabit is seen as a direct assault on them.") even if that part is embodied already in the passive damage of their encampment).
- A bonus to all "animal" tiles (deers, horses, cattle, sheeps, whales...) ("The religious beliefs of the Shoshone tribes stemmed from supernatural powers that often took the shape of animals and other mythical creatures.) Could be a bonus to faith or culture for instance (redundant with pantheons and OP probably).
- A random promotion for all recon lines unit (a bit like Japan's bushido) ("The Vision Quest is a ritual for the men of the tribe. If a man in the tribe has not had a vision or a dream, which the elders see as supernatural, they are then prepared to go on their vision quest. The premise behind the quest is that a spirit, typically in the form of an animal, will come to the tribe member and bestow its powers on him and become that man's guardian.")
- A bonus to all river tiles ("They were often referred to as the “valley people” because they camped in valleys.")
Most if not all of these ideas are probably ill advised or impossible to implement, but hopefully it can serve to show that there are a lot of possibilities to improve their UA beyond AR.
I'm not very knowledgeable regarding the Shoshone's culture and history but based on that reference (http://freebooks.uvu.edu/NURS3400/index.php/ch09-shoshone-culture.html, which seems credible albeit with strong Utah flavor

- A mechanic echoing their strong animism ("The Shoshone people were greatly connected to their land. They respect the native plants and animals and appreciate the land in which they live on. They believe that every plant and animal as well as the land itself has a living spirit and that the plants, animals and people maintain a relationship.") : it could be a bonus for any one/two unimproved tiles within their territory (synergy with their land claiming ability).
- Increased war weariness for the attacker pillaging/occupying Shoshone's tiles ("The Shoshone tribes believed not that they owned the land, but that they were one with the land in which they inhabited. They have such a strong relationship with their land that any damage done to the land they inhabit is seen as a direct assault on them.") even if that part is embodied already in the passive damage of their encampment).
- A bonus to all "animal" tiles (deers, horses, cattle, sheeps, whales...) ("The religious beliefs of the Shoshone tribes stemmed from supernatural powers that often took the shape of animals and other mythical creatures.) Could be a bonus to faith or culture for instance (redundant with pantheons and OP probably).
- A random promotion for all recon lines unit (a bit like Japan's bushido) ("The Vision Quest is a ritual for the men of the tribe. If a man in the tribe has not had a vision or a dream, which the elders see as supernatural, they are then prepared to go on their vision quest. The premise behind the quest is that a spirit, typically in the form of an animal, will come to the tribe member and bestow its powers on him and become that man's guardian.")
- A bonus to all river tiles ("They were often referred to as the “valley people” because they camped in valleys.")
Most if not all of these ideas are probably ill advised or impossible to implement, but hopefully it can serve to show that there are a lot of possibilities to improve their UA beyond AR.