Earth

Evolutionary History of Earth's Sentient Species
In the evolutionary history of the humans of ancient Earth, several sub-species survived into the modern era. From primitive primates came six species, humans, elves, dwarves, orcs, halflings, and gnomes.

Humans
Humans were the most common species on Earth, and still are on most of the worlds of the Realms, due to their quick lifespan and incessant drive to move themselves and their societies forwards. They were found on almost every land of ancient Earth. Their natural adaptability allowed them to live in the harshest deserts, the most frigid wastelands, and every place in between.

They were the first to build massive cities and were at the forefront of modernization in the later years of the First Era.

Dwarves
Dwarves were the first species to split off from ancient humans. While most humans moved out from the caves that had been their home for many millions of years, many stayed, developing their civilization under the Earth, rather than utop it. As time went on, those who remained developed the characteristic traits of modern dwarves, making them more suited to their mostly underground lives. Their increased sturdiness and strength also gave them an increased lifespan of several hundred years.

They were the first species to develop bronze, iron, and steel, giving them a high place among early civilizations. While their nations and civilizations were often more powerful than those of other species, they rarely used this used this power for conquest. Most dwarves did not want to leave the caves to rule over surface cities. While raiding did occur for rare artifacts and slaves, because most valuables in surface cities came from dwarven lands, there was little point in surface raids. What could be plundered could be gathered much easier from within the Earth. Raiding and other military action against other species was almost always primarily used to dissuade others from attacking dwarven lands.

As Earth moved into the modern era with humans at the forefront of modernization and technology, the high status of dwarves began to drop. Their natural proclivities to mining however, allowed them to stay ahead in mining technology, making them invaluable for those who needed rare resources.

Halflings
On the vast plains and grasslands of Earth, distances were long and food was scarce. While humans could survive, they had difficulty in doing so. In order to better survive in these conditions, the ancestors of the halflings shrank over time. Their now smaller size allowed them to consume less food and still remain healthy. It helped with the vast distances by allowing them to move faster and by making tamed horses more efficient.

For most of history, almost all halflings lived nomadic lives, following great herds of wild animals or tending to flocks of domesticated creatures. They interacted rarely with other species and civilizations and were left alone in turn, having no lands to take or riches to plunder.

After the onset of industrialization, the nomadic societies of the halflings began to dissolve as more and more of them moved to human cities. While members of other species had great difficulty when attempting to integrate into large human societies, the halflings had a much easier time. They were the most similar to humans, their only main difference being their size. Their skills were not prized as the skills of many other species were, however they faced much less criticism and dislike in human-dominated societies.

Gnomes
While they may appear similar to halflings, gnomes have a very different evolutionary history. Rather than diverging from humans, gnomes come from dwarven ancestors. They evolved to take advantage of the best parts of dwarven and human evolutionary strategies. Rather than living primarily in deep caves or on the surface, they adapted to a mix of the two. They lived and worked primarily in near-surface cave sections and shallow burrows, but would often venture to the surface for food and resources. For cave-dwelling communities, farms would often be created outside of the cave entrance, while the majority of residences remained within the safety of the cave. Burrow communities would often be more spread out and would dig their burrows near where they farmed and worked.

Due to their specialized niche, gnomes never reached the population levels of most of the other species, however their natural nimbleness made them excellent craftsmen. Jewelry and other riches created by gnomic hands would almost always be vastly superior and would fetch enormous prices in any part of the world. Their communities were small, but rich and while this assumably would make them a easy target for war and raiding, their caves and well-hidden burrows as well as expertly created defenses made attacking a gnomic village a tough challenge, if you could even find it in the first place. Their place in the outer areas of cave systems commonly put them in a place between dwarves and surfaces races in terms of diplomacy, trading, and war. Most trade with dwarven kingdoms would go through gnomic ones first. Many gnomic villages would also be sent soldiers from dwarven lands to act as a first line of defense.

Elves
Elves were the next species to split off from humanity. As humans spread to far corners of the world, elves evolved to take full advantage of the safest and most hospitable lands, losing their adaptability.

They most commonly settled in deep forests. Their intelligence and litheness made them exceptional huntsmen, allowing them to outthink and outmaneuver their prey. Meat was the bulk of their diet, unlike humans who depended more on farmland and crops. Due to their physiology's focus on specific climates and ecosystems, their average lifespans increased to around 400 years (this number would increase to around 700 during modernization). For the most part, they were calmer than humans and cared little about anything outside of their village. Trade between elven villages was rare and they would often only work together out of a common need, such as a great exterior threat. Their intelligence and dexterity made them excellent strategies and soldiers, and few who threatened elven lands lived to tell the tale.

As humans began to build great cities, a small portion of elves left the forests to copy this advancement. Most simply cleared land deep in the center of their forests and constructed their cities there, but a few cities were built on lush plains. Their cities quickly surpassed humanity's in terms of art and culture, but most often had little farmland, limiting their size. They also never surpassed human cities in terms of sheer productivity. The elves living in these cities were often more inclined to trade with other civilizations of elves and other species. Some even engaged in limited warfare, although their departure from their natural forests made them a much less overwhelming force to overcome.

Orcs
Orcs evolved around the same time elves did, but for the opposite reason. While elves evolved to fully use the most habitable lands, orcs evolved from the humans living in the harshest. Sacrificing intelligence and dexterity for pure strength and survivability, the orcs were much better at surviving harsh conditions. The orc species first evolved in the deserts where their strength allowed them to outcompete and drive out standard humans. They also had a much faster reproductive time, allowing their populations to grow faster and quickly recover from losses. While they commonly warred against and raided outside of their homelands, they were often outclassed in more habitable lands. Without the disadvantage of the harsh landscape, the intelligence of humans and other races allowed them to stop orcish expansion into their lands. Over time, some orcs moved to colder climates near the poles. After a few decades, they were firmly established in these areas and continued to spread.

While they very rarely created new technology themselves, they were adept at using it, even if they didn't understand its working. They remained a powerful force in the world until the onset of modernization, which allowed standard humans to give themselves many of the natural advantages of the orcs without any of the downsides.