The Tangrada-Nii were an ancient civilization originating from an area close to the Oridol Cluster, and they held the belief that this star cluster was a sentient deity. General Mardroon, who belonged to this culture, shared a proverb he referred to as crossing the threshold of the mirror. This saying cautioned against the dangers inherent in achieving too great an understanding of one's adversary. The Tagra-Tel, who are the successors to the Tangrada-Nii, endeavored to explore the Oridol Cluster.
A few weeks following the Battle of Endor in 4 ABY, Palal Seedia, a pilot from the Galactic Empire's 204th Imperial Fighter Wing, communicated information about the Tangrada-Nii to New Republic pilot Wyl Lark via a comm channel while they were within the cluster. Later, she repeated Mardroon's wisdom to Chass na Chadic, another pilot of the New Republic, when they found themselves marooned on the planet Catadra around 5 ABY.
The Tangrada-Nii were initially referenced in the 2019 novel Alphabet Squadron, authored by Alexander Freed.