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Skaro was made into a radioactive wasteland following a 1000 year long nuclear civil war between the Kaleds and the Thals. Nearly all life, plant and animal, on Skaro perished.
Due to the radiation levels there were many mutations leading to the birth of the Daleks.
When the First Doctor visited Skaro with Ian, Barbara and Susan he found a petrified forest, and the petrified body of a creature that was made extinct during the war. All trees were like stone, and the ground was turned to dust. No crops could grow.
The surface of the planet is barren and mountainous. The Dalek city visited by the First Doctor had an excellent natural defence for one side: an almost impassable mountain surrounded by a lake in which there are many ferocious mutations.
However in the TV Movie it appeared again at the start of the film
RECREATION OF SKARO
After the new Progenitor Daleks escaped, (Victory of the Daleks) they rebuilt Skaro (The Witch’s Familiar) the Dalek Emperor, their city of Kaalann and later their whole empire. The Eleventh Doctor discovered that the New Dalek Empire had invaded Earth in 1963. He went to the rebuilt city of Kaalann and discovered that the Daleks had found the Eye of Time, a Time Lord device that helped them alter Earth’s timeline. Using the Eye, The Doctor travelled to Kaalann in its ruined state before the return of the Daleks. He sabotaged the Daleks’ vision, allowing him to deactivate the Eye. The timeline returned to normal and the New Dalek Empire and their 1963 invasion of Earth was erased. Skaro reverted to its ruined condition. (City of the Daleks)
An area of the petrified jungle was salvaged by humans at some point close to the 41st century and taken to Earth’s Station 7 for research. (The Only Good Dalek)
The Eleventh Doctor revisited the devastated Skaro after being summoned by a woman called Darla, who claimed to have been looking for her daughter, Hannah. He did his with great reluctance, even going as far as avoiding calling its name. However, this was a trap to capture him; Darla had been taken over by the Daleks. (Asylum of the Daleks)
A dying Davros returned to Skaro, which had been completely restored by this point, after barely surviving the destruction of his Crucible at the hands of the Meta-Crisis Tenth Doctor, claiming “Where does an old man come to die? But with his children.” Davros later sent Colony Sarff to find the Twelfth Doctor and bring him to Skaro. The Doctor willingly came and was joined by Missy and Clara Oswald. The building Sarff’s ship landed in appeared to be a space station floating in space, but turned out to actually be on Skaro with the rest of the planet invisible to the rest of the universe. (The Magician’s Apprentice) The Doctor’s regeneration energy was transmitted to every Dalekon Skarowhen Davros apparently tricked him into releasing it into cables connecting him to the life of every Dalek. However, this was a ruse by The Doctor. The energy regenerated the sewer Daleks, who destroyed the Dalek city. (The Witch’s Familiar)