Ispar is the name of the planet where humans originate from. Ispar is the name of the only known landmass on this world, and is thus the name of the world. Ursuin, rats, cattle, and rabbits are also from Ispar.
Humans from Ispar are known as Isparians. The four heritages (Aluvian, Gharu'ndim, Sho, and Viamontian) currently found in Dereth on the planet Auberean are all Isparian, despite some uneducated players referring to Viamontians as a different race completely.
For more information see History of Ispar.