Historically there has been a division between two types of ages.
Light ages are typically represented by good communication, large, unified, monolithic forces bringing both knowledge, information, and change unilaterally to most of the world i.e. global evolution. Change tends to be in one direction for the entire civilization, whether that be progress or decline.
Dark ages are represented by poor communication, diverse entities (city states) and multiple conflicting forces and entities all changing independently of another. Historically, a sign of 'dark ages' is the lack of a comprehensive, consistent written history or records. The actual progress or decline of the period is separate from the presence or absence of records.
Once you separate out the idea of progress from the idea of a light and dark age, and instead view it as a societal structure, you gain a powerful tool in figuring out how to represent not only a traditional 'points of light' campaign, but also in how to run a game in a forgotten realms like place without it turning into "magic is a science substitute".
Some differing traits of the two types of ages:
- There is a single large default widely spoken language (common) in a light age era, versus regional languages based on a variety of different cultures or city-states.
- There are a collection of various empires controlling most of the known world in a light age era, versus decentralized collections of tribes, clans, or city-states.
- In a light age, communication, symbols, construction, and the like will likely be highly codified, regimented and therefore easy to understand. Dark age variations on such will likely be highly idiosyncratic.
- Light age citizens will fear a disease, idea, or other contagion that will destroy their way of life, while their dark age brethren will fear their neighbors and trust in safe-holds, castles, and fortresses to keep themselves safe.
- Light age systems and governments will be organized around hubs and hierarchies. Dark age systems of management will likely be direct interactions and agreements between individuals.
- Light age populations will likely be competing for ideals, attempting to convert various cultures. Dark age populations are exclusionary, insular, and ritualistic, outright rejecting conversion attempts.
One important thing to note here, is that whatever the trend is for the light age. it is universal. Whereas, in a dark age, some people will do well, some will do poorly, and many are going to be doing average.
This means that your light age game setting the trend can be a decline, not one of growth and order. It can be a decline similar to our current decline, where there simply is too much data to be illuminated and tracked all at once, or a decline similar to the decline of the roman empire, individual leaders, with out of date knowledge, doing whatever they did before until they hear again from the capital.
A large part of the cognitive dissonance when dealing with fantasy settings is handling how a light-age setting can fit with traditional fantasy assumptions (which often assume dark age settings).
I also find it kind of interesting that instead of assuming a dark age, Dungeons and Dragons carries many light age assumptions with it (single unified language, large empires controlling most of the world, etc.)
Understanding functioning light age structures (Discovery and settling of the new world, fall of the roman empire, explosion of information beyond human abilities to process) in light of the fact that light ages are never stable, but always on the rise or in decline, can assist with adding verisimilitude to those environments.
Hack & Slash