Aspects of Sime~Gen economy
Around the year -800 Unity, after a thousand years of chaos, several large Freeband Raider bands claimed a geographical region for their own, carving "Sime Territory" islands out of the landscape, and leaving the "Wild Gens" to themselves. Hence, Sime Territory is called in-Territory, (inside a perimeter) and Gen Territory is everywhere else, thus called out-Territory, (outside the perimeter of claimed land where Wild Gens live.)
These Raider Bands were able to settle into living in one place because they had possessed themselves of a very large number of Gens. Keeping the Gens prisoner until they were given (by the Leader) to renSimes for the Kill was cumbersome and expensive. Gens eat a lot, and the Raiders were nomadic and short-lived, and therefore didn't farm.
The singular genius who gathered such a huge band of Raiders to follow him (or her) invented the Pens for imprisoning the Gens, and re-invented "domestication" by breeding the captive Gens to make more Gens. They couldn't feed all those Gens, so they made the Gens farm the land to feed themselves. Hence the invention of the "Genfarm."
This Gen-based economy allowed for a Junct culture to develop.
The Pens couldn't supply all he Gens the Sime Territory required, but as the settled Simes bred faster than Freeband Raiders, the Leaders had to create the concept of "Licensed Raiders" -- those Simes who were licensed to harvest a certain number of Wild Gens and not damage the breeding capacity of the Wild Gen communities.
At this point, all Freeband Raiders were Simes who changed over out-Territory and fled the Gens who were intent on murdering them to prevent them from Killing. These Freeband Raiders would also raid in-Territory Pens, take over and destroy in-Territory villages of junct Simes.
The Junct Community gradually forgot that they were just a settled in band of Freeband Raiders and became functioning political entities. And for the most part, they were peaceful enough, but were at constant war with the surrounding Gens who resented being harvested for the Kill.
In this period known as the Territory Wars arose the First Channel at Fort Freedom. ( - 533 Unity)
The Forts, and later the Householdings that grew out of them, ( - 468 Unity) operated internally on a selyn based economy, often farmed cash crops or raised animals to deal with the surrounding junct economy.
At Unity ( Year 0 ) the Householding organization took over the gathering and distributing of selyn, supplanting the Pen based economy of the Juncts and eventually (very gradually) becoming the dominant force out-Territory among the Gens who merely donated selyn at a Sime Center once a month and were paid for their selyn.
The principle had emerged and gradually grown to dominance that Selyn is Currency -- a Medium of Exchange -- that crosses all borders.
With Unity, the pace of technological advancement picks up exponentially. Selyn becomes the main power source on both sides of the border, even before the borders are politically abolished.
Technology advances to where selyn amounts can be measured, at first only estimated by channels, and later measured objectively by instruments, stored in "batteries" and used to power vehicles, farm equipment, medical equipment, stage-effects equipment, communications such as telephone, and eventually computers and a form of internet.
Selyn power is cheap, plentiful, reliable, and best of all, requires no metal to transmit and handle.
With instruments, selyn can be precisely measured. It's unit of measure is the Dynopter, and that unit of measure eventually becomes the standard worldwide medium of exchange. The form in which it is handled, stored and transmitted changes again and again, as does the symbol by which it is known.
But Selyn is the currency that runs human civilization long before space travel makes it the currency of the galaxy.