At some point there is a thriving civilisation on Venus, which in our cosmos is an extremely unfriendly place. In this story it is stated that Venus had at least 25 dynasties, and thus a monarchical system. The Venusians may be known as Thraskins (or Plinges), these creatures having fingers and ears. Venusians' feet (i.e. what's at the bottom of their legs) are about a metre in length, and they understand the concept of politeness. One Venusian mile is equal to approx 4.5 Earth miles.
Venusians play a game like hopscotch (Death to the Daleks), have at least four eyes, and sing lullabies (The Curse of Peladon). It's a joke that you should never trust a Shanghorn with your Perigosto Stick (The Green Death). Venusians have developed a form of self defence that humans can also use (the Doctor calls this Venusian karate or aikido (Inferno)) which can permanently paralyse. There are seas of metal on Venus (Marco Polo) and flowers grow there (The Wheel in Space).
There is a Mars-Venus pleasure cruise in the 26th century (either to the Venusian civilisation or to a terraformed Earth colony there). The Doctor gained a pilot's license for this run at some point before 'Robot', and he visited the planet in his first incarnation with Susan (Marco Polo). The Eternals used the world as an obstacle in their race (Enlightenment).
In the 'space year' (Venusian) 17000 the Daleks attacked the planet, but were halted by the intervention of a fleet from the planet Hyperon (Genesis of the Daleks). The Venusians would seem to maintain interstellar alliances that Earth doesn't, and thus must have developed interstellar travel. Perhaps this Dalek attack also coincided with the Dalek invasion in 2164 (The Dalek Invasion of Earth).