Kingawa: The New Qin Empire

This is…something of an odd world.
Over a period of nine thousand years, the people of the Central Valley on the southwest coast of Tortolia slowly but surely started on the road to domestication. Unlike the rest of the continent, however, across which the trinity of beans, squash, and maize spread like wildfire, a trinity of one animal and two plants made themselves known in the valley. The earliest of these were the kechen or grapes (萄, vitis californica); natural California grapes are quite small and tart, but around nine thousand years ago varieties started to be grown that were larger and sweeter. The invention of wine came not long after, which seems to have spurred the creation of advanced pottery techniques. Shortly afterwards--perhaps as little as seven thousand years ago--efforts were made to take a strain of the lokosh or tule reed (schoenoplectus acutus). This allowed for the conversion of the riverbanks of the Sacramento and San Joaquin into paddies, and is perhaps the most fundamental element of Native Kingawan society. The plant provides a reliable food source, as well as a source of fibre for construction--and for papyrus-like scrolls, upon which the famous Codices were written. Finally, the haloo (鹿, ovis canadensis) or bighorn sheep was first herded around three thousand years ago, and takes up a lot of the grazing land in the valley. A reliable source of meat and a pack animal in a pinch, the haloo is smaller and fatter than its wild cousin.
These three together--combined with the early discovery of gold along the Sacramento, the open quarrying methods used to extract granite and marble from the hills, and the presence of a large field of meteoritic iron in Oregon--led to the development of a unique collection of cultures along the two rivers, Tortolia's only pre-Kurodan writing systems, gold-dusted mummies, and eventually the Bay Empire, which held for three hundred years and prospered...until the arrival of Kuroda Kiyoshi, of course. The story of the expansion of the New Qin Empire and the slow decay of the native Frenchmen (Kuroda's belief that he'd landed in France never quite went away) is a story for another time.
Oh, and add to that the fact that the Holy Roman Empire has the most extensive canals in the world, Mali has set up colonies in *Brazil, and Zoroastrianism has one heck of a big empire. Now it's an odd world.
This sounds positively mad and I immediately want to know more of the people along the Golden River.
I'll see what I can do!
Keep in mind that I do not, I repeat do not, intend for the following portrayals to be racist or racially stereotypical in any way. They are present for the purpose of constructing a narrative with quite scarce resources available on the nature of the original cultures involved. Should there be any corrections that can be made based on accurate information, I will quite happily alter the narrative accordingly.

The Seven Nations
In many a timeline the people of California, if considered at all, are wonderfully diverse and yet tremendously underpopulated. Split not into tribes, as one researcher described it, but "tribelets," the pleasant climate and easy access to food usually means that most have no particular need to turn to agriculture, which at least in the early days leads to a shortage of vital nutrients. Let us say, then, that some unusual factors came into play--a decade-long blight on the land, perhaps, or overpopulation, or even the imposition of raiders from the east demanding sustenance. And from that we get a California too like most other "civilized" parts of the world, one with a higher population but perhaps an unhappier one, and certainly one with less diversity of people.
But still, across the Great Valley and just to the south there are still six peoples of some importance, those who have held kingdoms in the Valley at one time or another, providing more variety in ethnicity than one might expect.
The Yokuts lay claim to being the oldest of the civilizations to take off the ground, certainly the first to commit to tule farming full-time as opposed to hunting and gathering. Even today their valley is famous for its variety and abundance of grapevines, and for the scores and scores of bighorn sheep grazing in pasture by the river. (Of course, it's also famous for coccidioidomycosis, which slowed their progress a bit as they periodically collapsed from getting too populous and moving too much dirt around.) Yokuts provided the basic format for clan professions as well, copied all across the Basin. Chieftains come from eagle clans, messengers from dove clans, town criers from the magpie clans, clowns and scholars from the coyote clan, and so on. Yokuts are slightly darker-skinned than others in the Basin, and are stereotyped as slow, stolid folk.
The Pomo are the great competitors of the Yokuts, living along the Sacramento instead of the San Joaquin. Their claim to fame lies not in their agriculture, but in their metalworking. Gold, of course, is something of an obvious commodity; even after all this time it's still possible to literally pan for gold in the northern streams, and it's a rare chieftain who doesn't lie in his tomb painted with gold dust. The Pomo had their origins just to the north of the Bay (it's big enough that it doesn't actually need a moniker), but spread to the Sacramento River Valley in the 9th Century CE, displacing the Wintun peoples. The Pomo have perhaps the longest faces of the Seven Nations, and are known for being zealously religious; the sweat lodges of their lands are famed across the basin, and they have a reputation as excellent shamans and magicians.
The Miwok are the latest up-and-comers in the river basin. Their initial residence was on the Sacramento-San Joaquin Delta, branching up both sides of the river and down to the Bay. For the most part, their emphasis lay in trade, and well were they served by their location, as a major source of the olive shells all tribes used as currency. Only three hundred years previously, however, they have done what neither side of the delta could have accomplished and unified the tribes under their own rule. Now the capital of the Basin lies in Hulpu-mni, slightly to the south of where Sacramento is sited OTL, and their variety of logograph is the standard for hundreds of kilometres around and even up and down the coast. Miwok moieties are split between Land and Water groups; each has their own Great Chief, the Land Chief taking care of terrestrial agriculture and military features, while the Water Chief deals with riparian trade and seafood harvests. (Tule reed harvests are considered the purview of both.) Miwok tend to have slightly rounder faces than their surrounding cousins, and have a reputation for being tough bargainers, jumped-up newcomers, and perhaps too clever for their own good.
The Ohlone live to the south of the Bay, and at one time occupied the spot where *San Francisco lies OTL. Living sandwiched between the Yokuts, Chumash, and Miwok peoples, they were slow to adapt and survived as a kingdom largely because of their technological advancements in terms of boating. For a long time nobody could beat the Ohlone for their swift canoes made of tule, and by the time the technology for new redwood canoes was imported from the Chumash, they'd gotten their hands on them and had started long-term trading missions with the civilizations of Mesoamerica. They are also a major source of abalone shells; although there have been attempts by one empire or another to conquer them entirely, their neighbours tend to be wary of going too far, lest their conquest spark a major war that the other powers would be sure to side against them in. The Ohlone are fervent tattooists and ear- and nose-piercers; non-Ohlone seem to view the elaborate designs as their most important distinguishing feature, as well as the beards and moustaches that the men tend to cultivate. The symbols the Ohlone paint on their bodies when they wish for some event to occur have found much use in protective charms across the Basin. Ohlone are seen as…well, a little strange, really, a little too worldly-wise.
The Chumash and the Tongva aren't even part of the valley at all; they live south of the mountains, in the area were OTL *Los Angeles and *San Diego are located. Living in perhaps the perfect place for hunting and gathering, with food supplies always in abundant reserve and little to fight over, these two ethnicities only started developing "civilization" (i.e. warfare, adobe houses, written language, etc.) after prolonged contact with the Ohlone during the 3rd Century BCE. Neither contributes very much to the empires to the north; neither really needs to. That said, the Chumash are still ruled by the astronomer-priests from their 'antap cult, and have literally the best calendar system in the whole *California area, to the point where the empires of the Basin to the north often send their shamans down to learn from them. The Tongva, meanwhile, act as something of a go-between station for the Ohlone and Miwok merchants from the north, and the Aztecs and Tarascans of the south. Their settlements on the *Palos Verdes Peninsula, in particular, have together become a single city-like area, known informally as Iyáanga or Poison-Oak Place, and is home to a great many camps of people. Many of the folk living inland or further along the coast view their relatives in Iyáanga as effectively uncouth sell-outs, but they do get a lot more beads, iron, and tule stalks that way. For the most part they are still bound by the precept that their chiefs must provide for their people through food and other means; a surefire way to become a chief, therefore, is to make a fortune in Iyáanga, be it through interpretation, bargaining, sexual favours, or music.
The Wintun are perhaps the most widespread of any of the peoples of the Central Basin, and yet have the smallest population, and are the ones most removed from their original culture. Their homeland along the Sacramento was long ago subsumed into the more powerful Pomo empire, which used its trade connections to make the first iron weapons. And yet the Wintun prevail, spreading themselves across the Miwok Empire, their position made essential to local rulers by their custom and practices. Which custom, you may ask? The spread of their religion, naturally. If the Pomo keep Kuksu and the other five spirits alive in the Sacramento Basin, the Wintun are responsible for spreading the six deities to the rest of California. They are sworn to an oath to record and repeat matters faithfully wherever they are; it's a surefire way to get news across the whole of the known world, and they are paid well by all six of the other major peoples for their trouble. Not in land, of course; the Wintun refuse to "own" land, believing this to be an affront to their exile. But in every other kind of material wealth conceivable, they do quite well. Thankfully they also invest this in the communities where they "pass through", so that many a new temple school or irrigation system has been paid for by their donations. Wintun are known across the Basin for their stocky faces and prominent foreheads.