Complex sentence: Although the poems themselves nominally depict events and characters from Hindu mythology, they are set in the landscapes of the islands on which they were composed, and therefore are a rich source of information about courtly society in Java and Bali.
Split into simpler sentences: Although the poems themselves nominally depict events and characters from Hindu mythology, they are set in the local landscapes of the islands. They are rich sources of information about courtly society in Java and Bali.