One of the earliest and most important Javanese king, about whom anything is known, was Airlangga, who ruled over Java and Bali in the 11th century. During his reign, Airlangga succeeded in uniting his kingdom and established strong cultural contacts further afield. Literature flourished and some of the major works of classical Javanese poetry were composed during this period. Not much is left in the way of temple remains, although there are a number of ancient bathing places, man- made cave hermitages and royal tombs to be found. Among them are the caves Selomangleng I and 11, located near Kediri and Tulungagung respectively, the bathing places of Jolotundo and Belahan on Mt Penanggungan, as well as the royal tombs of Gunung Kawi, which are carved into a cliff face at Tampaksiring in Bali. These latter are said to have been built for Airlangga's younger brother and his family, who continued to rule in Bali following Airlangga's death

source: eastjava.com