Saga of Pliocene Exile influenced by Celtic mythology
Influences
While the Saga of the Exiles and the Galactic Milieu series contain standard science fiction elements, such as time travel, aliens, metapsychic powers and futuristic worlds, May grounded her fantastical worlds in science, psychology, and mythology.May's studies in paleontology and climatology inform the Many Colored Land's geography, as well as helping readers to visualize the flora and fauna of the Pliocene epoch.  Both series are peppered with concepts from physics, genetics, higher mathematics, linguistics, human psychology, and Jungian psychology in particular.  
Mythology, however, appears to be the strongest influence on the Saga of the Exiles.  There are many parallels between the persons and places of the Saga of the Exiles and Celtic (and other) myths and legends.  The presumption is that such myths and legends result from the peoples, individuals, and events in this story, creating a loop that connects the present to six million years in the past.  The list below is far from exhaustive.