How to describe the span of 13,000 years in as many sentences, let alone a few paragraphs? It's an inhuman span of time, outside the realm of ordinary experience. There is no hook on which to hang a hat, so perhaps the best thing to do is describe those things that can survive so long: stones, stories, and people.
On the lost world of Texas, stones - and shards of pottery - can be found engraved with English words and letters. In "present day" Texas no one, not even scholars of ancient languages, can read them. For such is the constant mutability of language that even after a few centuries, someone using the South Midland dialect of North America circa 2010CE would be speaking gibberish - incomprehensible, but strangely disturbing in its familiarity.
Stories, oral traditions, have a surprising stability. The best known example on old Earth are the folk tales of Australian aborigines, separated from the rest of humanity for perhaps 45,000 years, four times as long as Texans. And Texans have their folk tales. There seem to be two branched origin tales. Both share the idea that Texans are not of their world, that they originally came from the stars.
The first set of myths and legends has it that the ancestors of Texans were gods up in the heavens, who over time bred and had children. But the offspring of the gods were weak and deformed, ugly and mortal. The gods, not being brutal, could not kill them, and so they left them there upon the earth, abandoned like a box of kittens on the side of a country road to fend as best they could.
The second set of myths has it that the ancestors of Texans were gods up in the heavens, who crafted the Texans out of mud and clay, and breathed a life and a soul into them. At first, the gods doted upon their children, and granted them their every fondest desire. But over time, the children became unruly, surly and ungrateful, and so the gods cast them down out of heaven, down to earth to fend for themselves.
Ethnologists who have studied both sets have surmised that the second set is based upon an older, more primitive narrative, as what archeological evidence that can be found does not support this conjecture.
(But imagine the surprise of archaeologists who, once the full scale colonization of their Moon was underway, having discovered the stash of records, technology, and mummified remains of the very first generation of wormhole pioneers, the determination that the very atoms of those ancestral mummies could not have originated in the Texan solar system).
What is common within the culture is the sense of abandonment, and an equal sense of resentment, and, paradoxically, pride in any technical accomplishment. Pride being the foremost characteristic of all folk tales. Humility is little found within the planetary culture, yet empty pretense is one of the foremost characteristics to poke fun at.
The concepts behind "All hat and no cattle" may be meaningless to the contemporary Texan, yet, if explain, he would readily embrace the phrase.
As to the contemporary Texan, viewed as a solitary individual, one who would have to say not uncomely, handsome in a rough and raggedy way, of large stature, robust, even beefy, but still retaining a surprising litheness.
This might be explain by both culture and environment. A love of strenuous activity and physical challenge is encouraged. And the native species of planet Texas do tend to be on the large side. The species analog of the wolf, for example, is the size of a lion. A lion as large as a grizzly bear. Bears are as large as rhinoceros. Bison as large as elephants. And elephants (or rather, mastodon, since the planet is a tad on the chilly side) as large as, well, mastodon. But that's big enough.
Albert Einstein tells us that my Now is not the same as your Now. We who inhabit the middles of things, in ordinary space, at casual walking velocities, at room temperatures, see things more like Sir Isaac Newton, who saw space and time as vast stage on which matter and energy played things out. His Now was the same Now as shared by everyone on that stage. Now, we know, not only is the same Now not shared within Einstein's relativistic frame of reference, but across the vast distances of the universe, with the indeterminancy of quantum mechanics, the passage of Nows varies. So, when you open a wormhole throat, the Now at the other end may be close to your Now, or a million years ahead or behind your now. For the fifty million people from Texas and its surrounds, who jumped through that wormhole, their Now got set back 13,000 years behind ours. This would be deeply troubling to Einstein, as it violates causality. But since this happens only through a wormhole, and this is expected, there's not much to be done about it.
Suffice to say, for the people of the new world of Texas, stranded some 60 million light years distant, some 13,000 years in the past, with perhaps the bare minimum seed corn needed to sustain a 21st century technology, and perhaps a billion person support shortfall, a Fall was inevitable. A series of tumbles at the very least. Fortunately, the level of technology on Texas never fell much past 1830s America. And, after a series of stumbles, but with a population growth at the biological maximum, with a culture fostering a healthy curiosity, they'd only five thousand years of relative barbarity to account for in Texan history. That left a good eight thousand years forward progress from a late 20th century level of technology.
You can imagine what happened. Peering through a peranoscope at Earth's own history, you find an average of about four thousand years to go from smelting iron to interstellar travel. Look through a similar peranoscope at the history of Texas - avoiding the usual Divergences involving nuclear armageddon, comet strikes, pandemics, etc. - the Texans did okay.
Rediscovering wormhole technologies, and doing Earth one better in coming up with a better than breakeven fusion technology (!), the Texans went on to colonize their whole galaxy. And as they worked their way up the technological plateau, heading further and further into our star-spanning, world-taming, cybernetic, mechanized, interconnected, informed, and hive-brained future, they still remained stubbornly human.
If what they went through in those five thousand years of our future could be called the Singularity, then it is interesting how they came out pretty much the same as when they went in.