The Eternal Empire of Zakuul's emergence had grave consequences for the Sith Empire. Darth Marr's execution left the Sith leaderless as the armies of Zakuul ravaged their worlds. Most of the remaining Dark Council were slain or went into hiding, and the once proud Sith Empire was forced into a humiliating surrender.
As the new Sith Empress, Darth Acina swore fealty to the Eternal Throne. Under her rule, the Sith were allowed to maintain authority over most of the planets they had conquered, though each world paid a substantial monthly tribute to Zakuul.
Severe restrictions were also placed on the Sith military, with strict quotas imposed on the number of ships and troops allowed to remain in active service. However, there are rumors the Sith secretly--and rapidly--rebuilt their military since Vaylin came to power in anticipation of a renewed bid for independence.