Planartouched: Gith

The Gith are an enigmatic race with conflicting origins stories. They have pale yellow skin, sometimes with greenish or brownish tones. Their skulls are long and angular, with deep-set eyes, flattened noses, and long pointed ears. Typical hair colors include black, russet, and sometimes gray. Githyanki are typically cruel, arrogant, and aggressive. The high value they place on individuality also causes them to become ambitious and self-centered. They are also known for their long memories. Even the most open-minded githyanki come across as smug, sarcastic, rude, and overconfident, but they are generally capable of withstanding adversity without complaining. Clever and resourceful, githyanki adventurers are not known for their loyalty or ability to make new friends, but they are extremely persistent in the face of danger. Although rare, it was possible for githyanki to become disillusioned with their people's unsavory habits and to try to set up a reputation on their own acts. On the other hand, the githzerai are ascetics and philosophers, pursuing self-knowledge in the face of adversity. A different side of the race, they are extremely distrustful of outsiders and are devoted to their self-preservation. An intense and sometimes fanatical people, the githzerai keep the memory of their origins always alive and carry out all their affairs with a burning sense of righteousness.
It all started during the First Age, The Titan War, when The Cube was created. At that time there were no Gith until The First Divergence, when history changed. Nobody knew that this event happened until millennia later but suddenly in the Astral Sea, a city appeared - Tu'narath, the city of Gith. To those that were able to mee the spacefaring race, they met the Githyanki archetype, who didn't use this name yet. The city was a tyrannical one as they served a Being From Beyond, who's name was forgotten or removed (this might be because of The Second Divergence). The race invaded the other places semi-frequently to gain new slaves, one such race was the Mind Flayers, which they enslaved using special dampening collars as they wanted psionics for war and communication. This trend continued for millennia as the race didn't intervene in many disasters that befuddled the Material Plane. This came to a strange turn after The Second Divergence and the city of Tu'narath was struct with a mysterious predicament. Half of their race changed, not only appearance wise but personality as well. The Mind Flayers were gone, instead ruined statues of them were all around. A split in the timeline happened. The Gith in the Githzerai timeline tried to enslave the Mind Flayers, only to be enslaved themselves. The city of Tu'narath was taken over in the Second Age, Godswar turning into a powerful base for the brain-eating creatures. They enslaved the Gith as their personal puppets and fodder in many wars in the Material Plane and beyond. However, one scholastic Gith, Zerthimon, was able to gain similar psionic abilities and achieved enlightenment, allowing him to defeat the Mind Flayers and free his people. Zerthimon is long gone, only his teachings survived in the Githzerai and now with their appearance a war civil broke out. The city of Tu'narath became a warzone. The Githyanki spend most of their time on mighty astral ships, sailing the Astral Sea. The Githzerai build secluded places in many planes, trying to escape their own race. While the historians assume the Githzerai are the race that appeared, it might be possible that the opposite is true as it is unknown what could it be the truth.

On Tethys

Githzerai like solitude, many of them follow the monk path as the teachings of their savior, Zerthimon, tell them to. Githyanki on the other hand are fierce warriors and pirates, that have little regard for other races. Both races fight over the city of Tu'narath, with some Mind Flayers as one of the sides, trying to retake them. The leaders of the Gith, Zerthimon and Vlaakith are believed to be alive. The former might have survived due to the strange time effect somewhere in solitude, while Vlaakith, the lich-queen of the Githyanki, might still dwell below the city, waiting for the right moment. Also, both Gith are serious about the past of their race, each side thinking that they are the original race, not the one that appeared with The Second Divergence, and while both refer to themselves as Gith, they do allow others to call them Githyanki or Githzerai respectively. 

First World

It is believed that there were no spacefaring races in the First World.

Gith

Ability Score Increase Based on Type

Size Medium

Speed 30 ft.

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Age. Gith reach adulthood in their late teens and live for about a century.
Size. Gith are taller and leaner than humans, with most a slender 6 feet in height.
Languages. You can speak, read, and write Common and Gith.

Gith (Githyanki)

Ability Scores: Str +2; Int +1
Alignment. Githyanki tend toward lawful evil. They are aggressive and arrogant, and they remain the faithful servants of their lich-queen, Vlaakith. Renegade githyanki tend toward chaos.
Decadent Mastery. You learn one language of your choice, and you are proficient with one skill or tool of your choice. In the timeless city of Tu'narath, githyanki have bountiful time to master odd bits of knowledge.
Martial Prodigy. You are proficient with light and medium armor and with shortswords, longswords, and greatswords.
Githyanki Psionics. You know the mage hand cantrip, and the hand is invisible when you cast the cantrip with this trait. When you reach 3rd level, you can cast jump once with this trait, and you regain the ability to do so when you finish a long rest. When you reach 5th level, you can cast the misty step spell once with this trait, and you regain the ability to do so when you finish a long rest. Intelligence is your spellcasting ability for these spells. When you cast them with this trait, they don't require components.

Gith (Githzerai)

Ability Scores: Wis +2; Int +1
Alignment. Githzerai tend toward lawful neutral. Their rigorous training in psychic abilities requires an implacable mental discipline.
Mental Discipline. You have advantage on saving throws against the charmed and frightened conditions. Under the tutelage of monastic masters, githzerai learn to govern their own minds.
Githzerai Psionics. You know the mage hand cantrip, and the hand is invisible when you cast the cantrip with this trait. When you reach 3rd level, you can cast shield once with this trait, and you regain the ability to do so when you finish a long rest. When you reach 5th level, you can cast the detect thoughts spell once with this trait, and you regain the ability to do so when you finish a long rest. Wisdom is your spellcasting ability for these spells. When you cast them with this trait, they don't require components.