Complex sentence: The land beneath the floating island, within the region it can travel, is known as Balnibarbi and is controlled by the king of Laputa, with the ground capital being the city of Lagado.
Split into simpler sentences: The land beneath the floating island, within the region the Laputa can travel, is known as Balnibarbi. Balnibarbi is controlled by the king of Laputa; its ground capital is the city of Lagado.