Life and Adventure
Humans, Elves, Dwarves, and Noomlings (Halflings) were the first intelligent races in the world. All civilization started with them. They each had a monstrous race constantly causing trouble: Gnolls, Orcs, Giants and Goblins. In those early times, the borders between dimensions were thin and the races traveled easily into the border planes. As they settled there, the still prevalent power of creation changed them.
In the Fey Wild four races became Changelings, Eladrin, Goliaths, and Gnomes.
For the Shadowfell it was Shade, Drow, Shadar-Kai, and Svirfneblin.
The elemental planes changed them into the basic 4 Genasi.
Some of these other planar races crossed back across the barrier and settled in the world eventually blending into society as one of its many oddities.
Humans, Changlings, and Shades found that they could breed with Elves, Eladrin, and Drow to make a Half-Elf or with Dwarves, Goliaths, and Shadar-Kai to make a Half-Dwarf (Mul). These sub races resemble a blend of their parents, but are unable to make more of themselves. Half-Elves can breed with any of the races that can make them, but always produce an offspring of that race as if they were one themselves. The same goes for Half-Dwarves. Genasi can bread with any of the races. The offspring can be either Genasi or the other parent’s race, though in the latter case they often display some kind of elemental abilities.
After the Titan War the twisted Gods, who would become known as the Far Lords, began to have a warping effect on the world. This created Psionic powers and many strange aberrations. The Githzerai race also formed from this and the symbiotic organism that lead to the Kalashtar as well. This effect also caused a mutation in the monstrous Orcs, creating the more civil minded Or-Kai (Half-orc). The Goblins were affected similarly, making Hobgoblins, which in turn adopted many goblins into a hierarchy. A small number of Gnolls began to join in with the societies set up by the other monster races. Finally, the Tinkerlings (Tinker Gnomes) popped into existence, like they had been around for ages.
People began to use their powers to create sentient automatons known as the Golemkind. Arcane and divine creators tended to make a more armored style, sometimes blending machines or flesh with various magics (Warforged). Primal casters imbued various plants and animal parts with spirits to create sentience (Wilden). And Psionicists used crystals to draw in a psychic personality (Shardmind).
During the Shadow Age, Revenants, Werefolk (Shifters), Minotaurs, and Kenku first appeared.
During the Age of Chaos, when dragons were everywhere, the Dragonborn and Kobolds entered existence. As did the rest of the Genasi types, Thri-kreen and Bladelings. When the bits of the Feywild started reappearing, it brought with it Pixies, Satyr, Hengeyokai, and Hamadryad.
After the Gods brought their realms to earth (the Divine Age), the Deva, Tiefling, and Vryloka races were born.