This is the first book of Mahabharata, and provides a number of key origin stories. It explains the origins of mythical objects, such as the amerta, the liquid of immortality, produced by the churning of the World Ocean. It also provides stories of origin of the key figures, groups or families from the Mahabharata. Thus the lineage of the ksatriya or nobles is explained, providing the ancestry of the Pandawa and Korawa families, the descendants of Bharata who will fight in the great battle later in the narrative. It also narrates the origins of the brahmins or brahmana, the priestly lineage who are at times in conflict with the ksatriya, and at other times their allies for the holding of ceremonies. Other key forces are presented by the divine eagle, Garuda, and the story of his obtaining of the amerta is narrated. The other important force in the cosmos is represented by the naga, the serpents who are Garuda's cousins. In various stories they interact with other groups.