Surakarta (Hanacaraka : ꦯꦸꦫꦏꦂꦠ, often called Solo and less commonly Sala, is a city in Central Java, Indonesia of more than 520,061 people with a population density of 11,811.5 people/km2. The 44 km2 city adjoins Karanganyar Regency and Boyolali Regency to the north, Karanganyar Regency and Sukoharjo Regency to the east and west, and Sukoharjo Regency to the south. On the eastern side of Solo lies Bengawan Solo River. The city is the seat of Surakarta Sunanate kraton. Together with Yogyakarta, Surakarta is the heir of the Mataram Kingdom that was split into two kingdoms in 1755.