A people whose colony was annexed by the Klingon Empire and then abandoned, and whose fleeing refugees were sheltered by Jonathan Archer, leading to his trial on Narendra III in 2152.
The Arin'Sen lived on a colony world near Klingon space that the Empire annexed, stripped of its resources and then left without support. A group of them fled in a small ship with little food or fuel.
As told in flashback in the episode Judgment, Enterprise answers their distress call and takes the refugees aboard. The Klingon battle cruiser Bortas under Captain Duras arrives and demands that the so-called rebels be handed over. Archer refuses and disables the Klingon ship rather than destroy it.
For this Archer is tried before a Klingon tribunal on Narendra III. His advocate Kolos argues the case with unexpected vigour, but Archer is still sentenced to the mines of Rura Penthe, from which his crew later free him. The refugees themselves are taken to safety.