A civil war on the planet Solum in a possible future, caused by disagreement over first contact with the Federation, whose survivors sent agents back in time to destroy Starfleet.
The Vau N'Akat civil war is the hidden cause of the events of Prodigy. As the Diviner explains to his daughter Gwyn in the first season, the Federation will one day make contact with his isolated homeworld, Solum. Some Vau N'Akat welcome the newcomers and others reject them, and the quarrel grows into a war that leaves the planet in ruins.
The last survivors blame Starfleet. When the experimental USS Protostar under Captain Chakotay comes through a temporal anomaly into their time, they capture it and fit it with a weapon, the living construct, that turns Starfleet ships on one another. They then send operatives into the past to find the ship, among them the Diviner and Asencia.
In the second season the young crew visit Solum before the war and meet Ilthuran, the Diviner's younger self. Asencia uses future technology to take power there, and her defeat offers Solum a different future.