What follows is an excerpt of what I've been working on (worldbuilding-wise), regarding the development of the 'contemporary' nations of Elyden. In a nutshell, the world is now populated by the descendants of the handful of survivors of the end of the previous age, who weren't forced to discover things for themselves as the original mortal races had...
Being a world of many pasts, the development of Elyden’s present Age had as its advantage various factors, not least of which were the ruins and remnants of past cultures. There was no slow rate of progress as one invention slowly appeared and became popularised, paving the way for other discoveries based upon its virtues. The survivors of the Fourth Age and its cataclysmic war found a world tarnished, filled with the ruins of their forebears, littered by the detritus of both war and peace.
We can never know what it is like for developing peoples and cultures to develop at a natural rate. Such a thing can only have happened once – following the creation of the Two-and-twenty mortal seeds and their eventual birth following the actions of the Demiurges – and even then, their actions were guided by the Demiurges. We of the Fifth-Age have inherited an old, used world. Many skills and technologies were either remembered by the descendants of the Fourth-Age or re-discovered through their exploration of the dead empire’s remnants.
Many advancements that took the first mortals centuries to develop; like husbandry, agriculture, organised trade and metalworking, amongst many others, were skills carried-forth from the old age. Tools lay rotten, disused, their forms echoing their one-time purpose. Skills were recovered far quicker than they originally took to develop, leading to an unnatural cultural development, where small groups of people – familial tribes or the retinues and followers of rogue leaders – advanced at a rapid rate. Within centuries, if not decades, of their re-emergence following the Fading of the Fourth-Age, these disparate group were wielding iron or bronze weapons of their own design (subject, of course, to the availability of resources and the logistics involved in their manufacture), erecting monuments and structures of a sophistication rivalling that of their forebears, and waging war with their neighbours over resources – raw materials and, as history tells us, slaves.
Dubbed the Renaissance of Rediscovery, this rapidity of advancement has, as records show, led to an aggressiveness that seems difficult to understand at face value. Unfortunately, there are little to no records of similar events having taken place in previous ages with which we can compare this phenomenon, but we can find theories.
Small groups of emergent mortals can be imagined to be a world onto themselves. They are isolated and restricted by the advancements and skills that their best members possess. Historically, all groups were on a relatively equal-footing, with most discoveries and inventions following a vague timeline. For instance, in the postulated first age of mortal live, the production of steel could not exist without a reliable history of extracting and smelting iron, itself a practice that favours agricultural communities with the resources to set up quarries and mines to excavate the raw materials, which would have required the development of husbandry techniques and the domestication of grasses and livestock.
The groups of people emerging from the Fading of the Fourth-Age had little of those constraints. The remnants of past cultures were all around re-emerging groups – disused mills, tools, quarries, raw materials, art, culture, coinage, and so on.
The mortals of the Fifth-Age are largely (though not exclusively) plunderers, building on the ruins of their forebears, having earnt little of their technologies and culture through toil, instead borrowing it from dead nations. As a result of this, things like currencies became prevalent quickly, using the treasures and coins of past empires for trading. Groups lucky enough may have found access to untapped natural resources – coal mines and iron-fields lying disused, awaiting extraction from the surface; overgrown fields, already sown with domesticated crops, and so-on. This led to a rapid growth in some areas, particularly in temperate and dry climates, such as mid-to northern latitude Llachatul and Meniscus, as well as southern Sammaea (though the latter two, being distant lands, have not been as thoroughly explored as Llachatul and the Inner Sea), with groups expanding rapidly thanks to the boons they found. Cultures developed quickly, inheriting the artistic traits of the ruins they raided, developing their languages around the written records they found.
So were the nations of Elyden’s Fifth-Age born; in the wreckage of those who fell before them.