As the 'Father of Therns', he got in trouble when their goddess Issus got killed. To get revenge on John Carter for dethroning his goddess, he abducted Dejah Thoris and Thuvia, who were imprisoned with his daughter Phaidor in a temple of Issus. He took them to Kadabra, whose jeddak (leader) is Salensus Oll. The Yellow Martians under control of Salensus Oll still belief in Issus.
When Salensus claimed Dejah Thoris as his fourteenth concubine, Matai Shang defied Salensus. Salensus shot Matai through the head as punishment, in front of his daughter Phaidor.
In Other Media
Matai Shang appeared in the film adaptation John Carter in 2012 as the main antagonist, played by Mark Strong. This version of Matai Shang is a far more proactive and formidable opponent, having access to lost technology that provides psychic powers, teleportation across planets and longevity. Shang, along with the Therns, have manipulated the course of civilizations in Barsoon (and its implied in many other planets) as they see fit, and gives their power to Sab Than, Jeddak of Zondanga in his war against the city of Hellium, for that very purpose.