Androzani Major was the twin planet of Androzani Minor in the Sirius system. It was the home of the wealthy and influential Sirius Conglomerate.
It was colonised by Earth, and the Doctor visited the planet during its early days. (TV: The Caves of Androzani)
By the 30th century, Androzani Major was part of the Earth Empire. (PROSE: So Vile a Sin)
Centuries later, it possessed a federal government, with a ruling body called the Praesidium headed by a president and an army called the "federal forces". The Conglomerate's chairman, Morgus, had great influence over the Presidium and was influential enough for the army's commanding officer on Minor to pass information on to him before the President. Spectrox, a chemical that could slow down ageing, was a major commodity and was harvested by androids.
When Sharaz Jek cut off the supply of spectrox, the federal forces tried to retake Minor and the spectrox, while Major's population and government panicked over the loss. Around this time, Morgus had also been laying off much of his workforce, and the unemployment was causing disruption on Major. The crisis ended with the deaths of Sharaz Jek, the President and Morgus. (TV: The Caves of Androzani)
In the year 5345, Androzani Major was using Androzani trees as a source of fuel. They used harvest rangers to affect this change. (TV: The Doctor, the Widow and the Wardrobe)