Board Thread:Lore Discussion/@comment-23371555-20140622024911/@comment-24999978-20140622160246

Xtremedue covered the Falmer rather well. As for the others;

The Dwemer were a race of Elves who lived most notably in Morrowind, which they named Dwemereth, but others clans also dwelled in areas in both Skyrim and Hammerfell. They were considered quite a technologically progressive race, and were not zealous about the gods as other races are. However, that is not to say they did not appreciate magic or the divine. There is a thin divide between magic and science in the Aurbis (the top mages are their closest equivalents to physicists, really, discerning how the Aurbis works) and their research into the natural order instigated by the Earthbones, for exampled, allowed them to create their ageless metal. As quite common amongst Elves, the Dwemer were not really content with their mortal existance, and strived to return to a primordial, Dawn state at the first interplay of Padomay and Anu. They attempted this reversal of subgradiency using their understanding of Tonal Architecture and the Heart of Lorkhan (the Missing God) to create the devestating, brass golem called the 'Numidium'. The Final Report to Trebonius outlines how the Dwemer attempted to bind their souls to the Numidium, as one stage of this plan, and many think their souls formed the Divine Skin of the Brass Tower. However, nothing is concretely proven as to what happened to the Dwemer after their disappearance at Red Mountain.

As for the Chimer, they split from the Aldmer in Alinor and followed the teachings of the Three Good Daedra (Azura, Boethiah and Mephala) turning their backs on the reverence of the Aedra. The followed the Prophet Veloth to Dwemereth, later named Resdayn (their name for the land) and then Morrowind, which was largely inhabited by the Dwemer, who they had conflicts with over the territory. The two did briefly unite against a Nordic invasion, cultminating in the First Council allying the Chimer, led by Nerevar, and the Dwarves, led by Dumac. The two appeared to get along well, but after reports of what the Dwemer were doing with the Heart in Red Mountain, the two warred in the War of the First Council. The Chimer were cursed by Azura after the battle (due to the murder of Nerevar by his friends, though accounts vary) causing them to become the dark skinned, red eyed Dunmer.

The Ayleids were the Hearland Elves who inhabited Cyrodiil, notably worshipping and forming pacts with the Daedra. Early Tamriel was rather dominated by Mer, and thus in Cyrodiil the human Nedes were held in slavery by the Ayleids. The construction of the White Gold Tower was instigated by them, and for the Tower's stone, Chim-el Adabal (The Amulet of Kings). Of course, later, in the First Era, the Ayleids were overthrown by a human slave uprising, led by St Alessia, supported by Pelinal and Morihaus (in particular) in addition to their Nordic allies in the North. While the Ayleid domination of Cyrod had been broken, some of them (likely those who had sided with Alessia) were able to retain some power. However, the rise of the Alessian Order, who were an incredibly anti-Mer organisation led by Marukh (of whom, the Marukhati Selectives instigated the Middle Dawn through the 'creation', for lack of a better word, of Akatosh, as we know him, from Auri-El), led to the final diminishing of Ayleids, many of whom subsequently fled to Valenwood, and others to High Rock, before the last Ayleid Kingdom (Nenalata) likey fell some time 1E 400-500.

There are more to each of these races than I have written which you make like to explore, such as the Ayleid figure 'Umaril' from Knights of the Nine, as I have written a brief bit about the rest of the races. I hope it is of use to you.