The Thoha were a tribe of Chozo known for their scientific prowess. They were the ones responsible for attempting to colonize SR388, consequently creating the Metroids. After remnants of their civilization were first seen in Metroid II: Return of Samus, the Thoha made their debut in the Chozo Memories of Metroid: Samus Returns, while the tribe's name was revealed in Metroid Dread.
The early history of the Thoha is largely unknown. They were one of the tribes to agree with the pacifist movement among the Chozo, foregoing their warrior traditions to instead focus on science. One or more Thoha were present on Zebes at some point, as a donor supplied their DNA to infuse into Samus Aran upon her adoption by the Chozo.
Although not specified in Dread, it is implied that the character Gray Voice from the origin manga was a member of the Thoha tribe, as he had donated his blood to Samus to allow her to survive on Zebes. Therefore, it is likely that Samus's Thoha DNA originated from him. She also received Mawkin DNA from Raven Beak.
Colonization of SR388
The Thoha were the Chozo who attempted to colonize SR388, building facilities within the planet's surface to study the natural wildlife and Aeion energy. They soon encountered the dangerous X Parasites and found no way to combat them with their current technology, not even with the help of the warrior Mawkin tribe. Desperate, Thoha scientists such as Quiet Robe created the Metroids as artificial predators to the X. As a failsafe, they programmed the Metroids to remain subservient to those bearing Thoha genes. This strategy was a resounding success, allowing the Thoha to explore SR388 deeper than ever before.
As the Thoha traveled deeper into the planet, they were able to access more and more Aeion energy. This energy had the unexpected side effect of causing the Metroids to metamorphose beyond their larval stage, growing much stronger and ignoring their loyalty to the Thoha. The tribe was forced to retreat from the caverns, sealing the dangerous evolved Metroids behind them with Chozo Seals and purple liquid. Both the Thoha and their Mawkin comrades had many casualties, but they managed to safely return to the surface.
On the surface, the Thoha proposed a plan to completely destroy SR388, deeming the planet a lost cause infested by both the X and the Metroids. However, Raven Beak of the Mawkin was obsessed with the great power shown by the Metroids and disagreed. He instead ordered a slaughter of the Thoha, sparing only Quiet Robe for the Thoha's affinity with the Metroids.
On ZDR, Quiet Robe endured the nightmare of the Mawkin and their X pandemic as the sole surviving Thoha. Quiet Robe was forced to create bioweapons for them and later hack the E.M.M.I., but was assassinated by a Robot Chozo Soldier shortly after divulging sensitive information to Samus Aran. This should have been the end of the Thoha, but Quiet Robe's remains were later assimilated by an X. This X reappeared as Samus fled ZDR, being absorbed by Samus so she could use Quiet Robe's Thoha genes to regain control of her Metroid powers.
- "Thoha" may be an anagram of hato 鳩 (pigeon or dove) (replacing the t with a th).
- With the genocide of the Thoha Chozo, Samus Aran is currently the only individual alive capable of quelling the Metroid and Metroid-related creatures solely in part to her Thoha DNA, assuming the Thoha's genes will not be revived back into existence through bioweapon technology.