I posted this on rpgnet and someone suggested there might be interest here.  I might run it as a pbem there if anyone is up for it.

Tribe
This game converts Nixon’s “Shadow of Yesterday” for use with tribes as player characters.

Pools

Might (Endure)
Anything where physical power is required;  covers most military applications.  Is refreshed when the tribe engages in athletic tournaments or funeral games with another tribe.

Diplomacy (React)
Covers negotiation, commerce, exploration and spying.  Is refreshed when the tribe has a holiday or religious festival.

Wisdom (Resist)
Covers cultural advances and learning.  In games where it is relevant, Wisdom also governs magic and prayer.  Is refreshed when the tribe produces a great work of art e.g. statue or totem, or a work of tragic theatre.

Possible skill levels:

0 Primitive (default)
1 Competent
2 Expert
3 Advanced
4 Legendary

Skills:

Archery (M) Ranged Combat

Architecture (W) Also includes engineering.

Beasts (M) Riding, beasts of burden, using beasts in warfare etc.

Commerce (D) Negotiation and barter.

Create (W) Making art, totems etc.

Custom (D) Savoir-faire, knowing how “it is done” in other parts of the world.

Deceive (D) In negotiations with other tribes.

Farming (W) Agriculture for a city-dwelling tribe, herding for a nomadic tribe.

Healing (W)

History (W)

Intelligence (D) Discern Truth in negotiations with other tribes.
Land Lore (D) Knowing the lie of the land, navigation etc.

Melee (M)

Music (W) Music, poetry and dance.

Movement (M) Get around at speed.

Myth (W) Producing and encoding shared cultural truths.

Philosophy (W)

Pray (W)

Scouting (D) Opposes Stealth.

Seafaring (W) Also covers naval combat.

Stealth (D)

Subsist (D) Hunting and taking food from the land;  not farming.

Sway (D) The ability to persuade other tribes in negotiation.
Tactics (M) The ability to use land, weather etc. to your advantage in battle.
War Machines (M) Make and use weapons and siege engines.

Women (W) Your tribe’s development with regards to women.  Covers their emancipation, education etc. and any rolls involving women.

Sample Tribes
(only for use as examples- the game is intended for use with player invented tribes;  it is better if nation philosophies and special moves are created rather than ripped off )

Carthaginians
Might 8
Diplomacy 4
Wisdom 2
Expert Skills
Endure (M), Tactics (M)
Competent Skills
React (D), Beasts (M), Melee(M), Scouting (D)
Primitive Skills
Resist (W), everything else.
Secret of the Elephants (weapon) adds +1 harm when using Beasts only on open plains (no good in forests, swamps or mountains). 
Secret of the Commander ;  Hannibal is an unrivalled tactician.  The Carthaginians may spend any number of might points as bonus dice on a tactics roll, rather than the usual limit of one. 
Key of the Vendetta The Carthaginians wish above all else to destroy Rome.  They gain 1 XP whenever they hurt Rome, 2 whenever they strike a minor blow and 5 whenever they strike a major blow (GM’s decision is final).  Buyoff:  Make an alliance with Rome.
Key of the Pleasure Seeker  The Carthaginians are renowned for their softness if exposed to vice and luxury.  They gain 1 XP every time they take time out to indulge their passions, 3 XP whenever they change a plan to take up an opportunity to indulge in pleasure.  Buyoff:  Refuse the gift of hospitality from another tribe.

Minoans
Might 3
Diplomacy 4
Wisdom 4
Expert Skills
React (D), Commerce (D)
Competent Skills
Resist (W), Seafaring (W), Pray (W), Music (W), Myth (W), Architecture (W), Melee (M)
Primitive Skills
Endure (M), everything else.
Secret of the Labyrinth  “They have a cave Troll!”  Well, actually, it’s a Minotaur, and it gives  a +1 to all myth rolls which centre on their own capital city.
Secret of the Labrus  The Minoans are armed with their distinctive sacred axe, which gives them a +1 harm in melee against unarmoured opponents.
Key of Human Sacrifice  The Minoan bull-god requires a regular diet of virgins from other nations.  Gain 1 XP whenever they take virgin prisoners from another tribe and 3 XP whenever they have the chance to send them into the labyrinth as part of a major festival (which also restores their diplomacy pool).  Buyoff:  Aid a prisoner to kill the Minotaur…
Key of the Rumbling Earth  The earth around the Minoans’ island rumbles ominously.  Gives them a +1 armour against Land Lore whenever they are defending their home.  Buyoff:  Sustain a major earthquake or flood.

Romans
(would not be an intial player character – this is a souped-up NPC created for the scenario below)
Might 8
Diplomacy 4
Wisdom 6
Advanced Skills
Tactics (M), Endure (M)
Expert Skills
Resist (W), Melee (M), Scouting (D), Sway (D)
Competent Skills
React (D), Architecture (W), Commerce (D), Myth (W), History (W).
Primitive Skills
Everything else
Secret of the Tortoise Formation  This famous formation gives the Romans +1 armour against archery. 
Secret of the Aqueduct  This technological wonder gives the Romans +1 to architecture rolls that involve irrigation, plumbing and sewage.
Secret of Virgil  (x2) The ultimate mythmaker.  Gives the Romans a +1 harm to conflict rolls on History or Myth.
Key of the Neighbour  The Romans are always looking to expand their Empire and civilise or destroy their neighbours.  They take 1 Xp whenever they receive significant tribute from a neighbouring nation they have not conquered.  They  gain 3 whenever they conquer or destroy a neighbouring tribe.  Buyoff:  Make an alliance with a neighbouring nation.

Advances
Your race begins as a band (5 advances);  when you have spent 10 advances, you become a tribe, and so on according to the table below:
Band (5 advances)
Tribe (10 advances)
People (25 advances)
Nation (50 advances)
Civilisation (100 advances)
Feats of Legend
Whenever a race scores 7 on a roll (a legendary skill level combined with +++), they achieve a feat of legend.  As well as a cool description, they immediately gain a number of free advances according to the table below:
Band Not capable of such feats
Tribe 1 advance
People 2 advances
Nation 3 advances
Civilisation 4 advances

Example of Play
(This ain’t a history lesson, alright?)

The Carthaginians and the Minoans (I did say this was just an example, right?  And that it wasn’t a history lesson?) have formed an alliance to take on the Romans.  The Minoans are always looking for fresh virgins to feed to the minotaur, and the Carthaginians have their vendetta against Rome, so both stand to gain XP from this project.  Bob is playing the Minoans and Henry is the Carthaginians.  The Romans are a NPR (non-player race) controlled by the GM. 

Henry and Bob have done their homework and gathered intelligence.  They know that Rome is a powerful nation, but they think they might be able to take them on if they pair up, particularly because they plan a quick sneaky raid to grab women rather than an all-out battle.  Henry (Carthaginians) would like to try meeting the Romans on the open plain, but Bob figures he is safe retreating by sea from any conflict back to the safety of his island, where the Minoans are pretty well defended.  He also knows that the Romans are not a great seafaring nation, and that if they come out to the island, there is a pretty good chance that the myth of the minotaur could keep them at bay. 

The plan is to attack swiftly by sea and snatch a shipful of Roman virgins.  Bob and Henry both agree that this is their intention in the free and clear stage:  to snatch a shipful of virgins.  The GM declares that the Romans hope that their scouts alert them to the attack – their intention is:  to destroy the raiding party. 

Bob and Henry are making a simple assisted roll.  The Minoan seafaring (2) roll will add bonuses to the Carthaginian stealth  roll, which is unfortunately only at primitive (0) level. Both Bob and Henry elect to spend a die from their pools to increase their chances of success.  The Romans roll scouting (2), and also spend 1 die from their  Diplomacy pool. 

Bob rolls 0, +, -, +, the – is subtracted for a total of 2, which added to seafaring gives a total of 4, all to be rolled as bonus dice by Carthage in addition to their bonus die from diplomacy.  Henry rolls 0,+,-,-,-,0,-,+.  Removing the 5 lowest dice, he gets 0,+,+ for an overall total of 2;  he has nothing to add from his primitive stealth.  The Romans roll -,0,+,0, giving a total of 1 once the – is removed.  Added to scouting (2), they win with a total of 3. 

The GM rules that the Romans crush the scouting party.  Henry wants to bring down the pain – he is not happy with this result, however Bob knows when he is beat.  Henry knows that he doesn’t have a chance without Bob, so he vows to return with a tougher  ally.  Neither Henry nor Bob gain XP from this encounter, but apart from that they come off relatively unscathed as they backed out when the stakes were low.

Meanwhile, the Romans prepare their counter-offence…

This is a really interesting idea; TSOY as boardless campaign war game!  I can also see how integrating this into a normal game would be a lot of fun.  For example, in my current Pirate game, I could have the Spanish Empire as a TSOY character, representing the entire culture whenever the player characters are interacting with its official arms (customs inspectors, island governors, etc.), instead of each character individually, or in addition to each character individually.  For example, the player characters must negotiate with Don Reynaldo, Governor of Cartagena.  But in the actual conflict, there are really two NPC's, Don Reynaldo and the Spanish Empire (representing Reynaldo's ability to call on troops, money, officious bureaucrats, etc.).

I routinely use a single character (usually with one good size pool such as Vigor) to represent a number of people ("Crew of the Rosy Cross", "Troop of Escaped Slaves"), this is taking that idea to a whole new level.