The Kallidahin, also known as Polis Massans, were a race of sentient cetaceans native to the world of Kallidah, having obtained their misleading name due to their extensive century-spanning digs on their adopted home in Polis Massa. The Kallidahin lacked facial features and were commonly mute, resorting to signs and telepathy to communicate. Though they had little contact with other species and were considered hermetic, they were known for their extraordinary medical, archaeological and xenobiological skills, and were regarded as compassionate beings who understood the value of life. They were also known for their massive xenobiology database. The Kallidahin joined the Alliance of Nations.