A History of the Whoniverse
The Thirty-first Century (3001-3100)
As the 31st Century began, what remained of the Empire was in tatters. Colonies were increasingly opting to leave the Empire, the Landsknechte Corps had fallen, and several former colonies were beginning to become space powers.
[This is the background to The Sorcerer's Apprentice.]
THE SORCEROR'S APPRENTICE
The Empire's military discovered that a large number of spacecraft had disappeared near the planet Avalon. An expedition was sent to investigate the possibility that the planet hid a super-weapon. They discovered that the planet housed powerful nano-technology that destroyed all electronic equipment. However, the technology was destroyed before they left.
[There are a variety of different dates we could settle on. The discovery of a ship built in 2976 (page 17) suggests that it's the late 30th Century (pages 33 and 48). The colony was founded in 2145 (page 203), which was 846 years ago (page 33), making it 2991. Despite this, events in Original Sin (2975) are clearly stated to have been 50 years ago (page 156), and the Empire has severely deteriorated since then. Perhaps the chaos which led to the establishment of Avalonian society wiped a few decades from the calendar, or the Avalonian year is about 14 days longer than the Earth year.]
Late 31st Century
Towards the end of the century, colonists from the Overcities began to rebuild Earth. One group, the Concocters, constructed Europa. This turned Europe into a model of Europe between the 14th and 19th Centuries. Europa was created by Mimesis, an ancient Gallifreyan art, which had been learnt by a being called Mimic.
[This is the background to Managra. Europa was created about 200 years before the book.]