The Drahvins had a rigid caste system. On top were the Elite, with the scientists, leaders and military commanders. They could be identified by their scarlet clothing. They were allowed actual food, could vote and had a normal birth. Below the Elite were the slave class, which did menial labour. They were artificially created and were given limited intelligence and creativity. They would be given a number instead of a name (such as "Drahvin One", "Two" and "Three"), were fed on food pills and were expected to obey the Elite without question. Males had no part in this system and only a small number of males were kept alive for reproduction, the rest being killed to preserve resources.
The Drahvin government was split up into Ministries, such as the Ministry for Offensive Research. Though the Elite had a vote, there was only one political party and little actual change. (PROSE: Galaxy Four)
Drahvins did not understand the concept of giving one's life for an individual. Failure was considered inexcusable and it was standard policy among the military Drahvins to shoot the wounded. (TV: Galaxy Four)
The Drahvins had somewhat limited technology. For example, their ships were made of common metals, making them functional but not particularly durable. They used guns physically similar to the machine guns of Earth, but which used energy instead of bullets. In an attempt to stop the Chumblies, they also used a mesh-net which could incapacitate them. (PROSE: Galaxy Four)
At some point in their history, the Drahvin homeworld, Drahva, was undergoing a dramatic drop in temperature, killing the vegetation and forcing the Drahvin to find new planets to colonise. One ship, led by Maaga and with four Drahvin slaves, encountered a Rill ship. The Drahvins attacked, but were defeated, causing them both to crash onto an uninhabited planet. The planet was doomed to destruction and though the Rills wanted to work together with the Drahvins to escape, the Drahvins attempted to take the Rill ship by force. When the First Doctor, Steven and Vicki came to the planet, Maaga tried to trick, then force the Doctor into helping them destroy the Rills and escape the planet, but failed. The Drahvins died when the planet exploded. (TV: Galaxy 4)
The Drahvins attempted to invade Earth some time prior to 1997. UNIT fought them off without the Doctor's assistance. (PROSE: The Dying Days) By 2005, Torchwood Cardiff had acquired a Drahvin scanner. It was procured by Yvonne Hartman, who hoped to use it to unlock the Void Ship back at Torchwood London, only to lose it in a fire. (AUDIO: One Rule)
On 17 November 2900, the Drahvin conquered Tivoli, eradicating the Shakri. The Hath returned to the planet (centuries after their original occupation of it) on 8 December 3001 and drove out the Drahvins. (PROSE: Time Traveller's Diary)
The Drahvins were among the races who joined the Alliance. They came to Stonehenge in 102 and helped imprison the Eleventh Doctor in the Pandorica in order to save the universe. (TV: The Pandorica Opens)