The Wurm planned to take over the home planet of the peaceful Valnaxi which, due to its position, would allow them to conquer the rest of the galaxy. The resulting war grew to span the seventeen systems of the Wurm Empire.
By 118 the Valnaxi had no chance of winning. They hid all their treasures, including the Lona Venus, The Flight of the Valwing and The Shriek, across the galaxy, hidden in warrens on different planets, including Earth in Africa. All were guarded by Golems as part of their trap for the Wurms. For two thousand years, with the Valnaxi extinct, the Wurm searched for the warrens with the aid of Jaxamillian Faltato, to crush every last representation of the Valnaxi.
Seven chosen Valnaxi landed on Earth in a spaceship that was buried for thousands of years. In 2118, the Wurm found what they thought was the greatest warren, on Earth. They invaded Africa to crush it. By that time the Valnaxi Council had lost their bodies and their intelligence was contained in smoke. They had set a trap with a fake deactivation plaque for the Wurms to find, thinking they were deactivating the Golems. The Wurm had encountered Golems at every warren and were conditioned to fight them. The Valnaxi fooled them. As soon as a Wurm touched the plaque, its physical and psychic abilities would be copied and reproduced so the entire Valnaxi race was reborn and travel back to their Wurm-infested home world, allowing them access to the spirit of their planet.
This trap was ruined, however, when Solomon Nabarr touched the plaque and they were given the human form to copy. They sought out Rose Tyler to have a female version, finding two sexes necessary but viewing the human reproduction process as clumsy and inefficient. A male and female were created as templates, but the Valnaxi planned to turn all humans into Valnaxi so they could fight the Wurms.
Through the Tenth Doctor's intervention, King Ottak was killed and the Valnaxi ship was sent into space by a volcanic eruption so the fighting would leave Earth. The male and female stayed behind. (PROSE: The Art of Destruction)