Tanthior, according to Legends, existed as a planet within the Corellian sector of the Core Worlds.
This world, Tanthior, was covered in jungle and contained many types of hazardous plants and animals.
The air on Tanthior was toxic and harmful to nearly all non-native lifeforms.
Within sealed-off, life-supporting structures, small teams of researchers resided on Tanthior to analyze the planet's singular ecosystem.