Whilst everyone on Amaranthine may fall under the blanket term "Amaranthian", certain nations and groups developed quite differently. Below are just a few examples of such diversities, referred to canonically as "cultures".
The Magi were the ruling class of Amaranthine. To be Magi is to be related to the very rulers of the Old Kingdom; a claim that cannot be made by many. Indeed, many who make this claim lack any proof, and do not show the traits associated with true Magi.
Magi are well known for their innate Aether control, favouring the school of Manipulation. Being gifted also in the art of combat and speechcraft, it is not surprising that they were the most dominating culture, despite being such a minority.
The Nobility are often mistaken as a lesser version of the Magi, when it would be more accurate to refer to them as a greater version of the Commoner. Lacking any innate Aether control, the Nobility relied heavily on their positions as notable politicians and leaders.
Chances are, if you come from a wealthy, notable family but had no direct claim to the throne, you are a Noble. Many nobles also served as officers during the Calamity.
The Commoners once made up the largest majority on Amaranthine. Developing over a long period of time to survive often with little food, the Commoners were often master tradesmen and unmatched in most manual labour. As a result, many rich and successful Commoners did exist, although their traits made them much less notable than the Nobility.
Often training in the arts of direct combat, many armies were primarily made up of Commoners as footsoldiers.
All pure-blood Psyians are now extinct, save one (Komid). Once a booming culture with a large capitol (Balseraph) and smaller cottages surrounding the area, the time era shortly before the Calamity. They branched off from the rest of Amaranthine early after Amaranthine's creation, and became fairly self sufficient, having Balseraph as their main residence. About 1143 KL, the majority of the Psyian race disappeared, with less and less Psyians appearing out of Balseraph
They are known for an innate Aether control, not unlike the Magi's. Unlike the Magi, however, most Psyians prefer Elementalism. Most Psyians despise Magi for their royal blood, and the way Magi look down on Psyians.
Psyian blood still exists, however, in that some Psyians left Balseraph, for unknown reasons, to settle down in the rest of Amaranthine. But all of the full-blood Psyians passed away long ago, mostly due to old age. Having some Psyian blood seems to have a positive effect with learning Aether relative to how much Psyian blood is in the person.
It is not known how many are left, but it is guessed there are not a lot. There is also a rumor there is a ceremony to add Psyian blood to someone, if one wanted to investigate this, they would ask Komid.