Eldar

The Eldar are an immortal non-human species inhabiting Plethira, who were created by the Old Ones so as to continue the existence of their knowledge. Their society predated the crossing of men over the Great Ocean by around 10,000 years. Over the course of the First Wars, the First Cataclysm and many thousands of years, all females died (the Red Plague outbreak) and the men steadily dwindled until even the last mansion, Non Selpossis, was effectively abandoned.