The Malakh were known for their aggressiveness. Sarah Jane Smith once said that they would start a war against you "just for looking at them".
The Uvodni Empire was backed by an alliance of other races. However, the Malakh eventually defeated them all during the course of the Ghost Wars. Because of this, the Uvodni needed to find some more allies, and fast.
They came upon Earth and found that the native sapient species, the humans, were a good choice as they were naturally aggressive. In the 20th and early 21st century, the Earth missions were controlled by General Uvlavad Kudlak, who was taken from the front lines in 1988 due to injury, and his Mistress, a computer. Their aim was to abduct human children to send off to the battlefields. The mission was carried out under the futuristic war game Combat 3000. (TV: Warriors of Kudlak)
End of the wars
In 1998, the wars ended with a truce between the Uvodni and the Malakh and the Uvodni Emperor ordered the Imperial Fleet to return home, but the Mistress was not designed to recognise peace. She hid the message from General Kudlak for ten years until found by Luke Smith after hacking into the computer systems of Kudlak's warship in 2008. Until then, Kudlak continued sending children onto battlefields.
Kudlak was shown the message. Angry at the new-found knowledge that his Mistress was a computer and that ten years and many innocent lives had been wasted, he destroyed the Mistress. He sent the children on board his ship back down to Earth, where they were returned to their families. He returned to his homeworld to find any surviving children from previous transmissions to the battlefields to return them back to Earth. (TV: Warriors of Kudlak)