The Valnaxi were a race of bird-like artists.
The Valnaxi were an avian species. They were extremely telepathic and had a link with their home planet. Their home planet had a spirit which they connected to for inspiration and without this connection they were unable to create art. (PROSE: The Art of Destruction)
The Valnaxi were not very skilled with technology, being more adapted to art, and it took them a long time to develop any new technology.
The only known technology used by the Valnaxi were in the treasure troves. These treasure troves were carved out of the rock and guarded by specially created guardians. A gold substance was produced out of magma, which in turn was formed into mobile blobs. This gold substance attempted to cover any living creature, infect it and modify its DNA to turn it into a guardian. (PROSE: The Art of Destruction)
The Valnaxi were extremely gifted artists, creating at least statues and paintings, possibly more. Instead of using canvases, the Valnaxi used a sticky, web-like material for their art. Some of their known artwork include Lona Venus, The Flight of the Valwing and The Shriek. (PROSE: The Art of Destruction)
The Valnaxi became involved in a war with the Wurms, which was ending by 118. During the war, they attempted to hold onto their planet for as long as they could, but they were eventually forced to leave. They attempted to create treasure troves, filled with their greatest art pieces and set the guardians to protect them. Each treasure trove had coded directions to find the next treasure trove, leading to the final warren on Earth in what would later be known as Chad.
In reality, the treasure troves were traps to lure in the Wurms. The surviving Valnaxi turned their consciousness into smoke and hide in a spaceship under Mount Tarsus. There was a special panel in the final treasure trove that would absorb the DNA of the Wurms and create new bodies for the Valnaxi. They would then be able to return to their home planet without raising suspicions.
Unfortunately, instead of it taking 300 hundred years to find the treasure troves (as the Valnaxi believed), it took the Wurms 2,000 years to find the last. In addition, instead of Wurms being the first to find the panel, a human called Soloman Nabarr reached it in 2118. As a result, the new Valnaxi forms were accidentally made in the image of humans instead of the Wurms. In order to try to perfect the process, they also kidnapped Rose Tyler to use as a base for a female. Seeing that the humans reproduced too slowly to recreate the Valnaxi, the Valnaxi then decided to infect the humans with the magma guardians, recreate them and replace their minds with those of the Valnaxi. This plan was stopped by the Tenth Doctor, who launched the spaceship with the Valnaxi consciousnesses inside. (PROSE: The Art of Destruction)