Located far in the Outer Rim, in the Faylar System, Dreven became the perfect place for the Empire to establish its capital following the Fall of Coruscant in 4 ABY. Castle Tsabak was located here, where would-be emperors and warlords would sit in their seats of power, and where the Interim Ruling Council would take up residence.
Imperial High Command fled to Dreven, consolidating their power and preparing to strike back at the New Republic. Warlord Valak, with the backing of the entire Empire, proclaimed himself Emperor from Castle Tsabak in 6 ABY, but this was not official until his formal coronation in 8 ABY. And from Dreven, under Valak's control, the Empire struck back, reclaiming a great amount of lost territory over a period of several years.
But as the war raged on in the Empire's favor, Dreven was soon forgotten, put into the back of galactic politics as planets closer to the Core took to the forefront. With Kendal Osbourne's ascension to the throne, the Imperial capital was transferred to Selene, where a new Imperial Palace had been constructed.
Dreven remained untouched by the war, too remote to catch the attention of the waning New Republic. The dark and mysterious planet, however, would find itself the target of its own people, during the War of the Throne and later with the rise of Darth Malign and his purge of Emperor Malus's supporters.
Dreven found itself the capital of the Galactic Empire one more time after the destruction of Selene, but the capital was once again returned to Selene after its reconstruction. As of 14 ABY, only the Imperial Royal Court and upper-class Imperial citizens reside on the forgotten planet.