Subak is the water management (irrigation) system for the paddy fields on Bali island, Indonesia. It was developed in the 9th century. For the Balinese, irrigation is not simply providing water for the plant's roots, but water is used to construct a complex, pulsed artificial ecosystem that is at the same time autonomous and interdependent. The system consists of five terraced rice fields and water temples covering nearly 20,000 hectares. The temples are the main focus of this cooperative water management, known as subak.