- You may also be looking for the planet of the same name.
The Menk were one of two humanoid species native to the planet Valakis, the other being the Valakians. Their nation, the Commonwealth of Menk and Valakis, became a member of the United Federation of Planets in 2236. (ENT episode: "Dear Doctor", ST reference: Star Charts)
By 2151, they were primitive and relied on the Valakians for clothes, food, medical supplies and land to live on. They also had a language that the universal translator was unable to translate, but was easy enough to learn.
When Enterprise visited Valakis to find a cure for the Valakian plague, Doctor Phlox researched the Menk's immunity to the disease. He later discovered the Menk were evolving and convinced Captain Jonathan Archer to leave the Valakians to attempt to discover a cure of their own. (ENT episode: "Dear Doctor")
By 2236, the Menk had become dominant, with their population reaching millions while the Valakians had only a few hundred thousand people. They had discovered warp technology in 2236 and were admitted to the United Federation of Planets shortly thereafter. (ST reference: Star Charts)