Bali is part of the Coral Triangle, the area with the highest biodiversity of marine species especially fish and turtles. In this area alone, over 500 reef-building coral species can be found. For comparison, this is about seven times as many as in the entire Caribbean. Bali is the home of the Subak irrigation system, a UNESCO World Heritage Site. It is also home to a unified confederation of kingdoms composed of 10 traditional royal Balinese houses, each house ruling a specific geographic area. The confederation is the successor of the Bali Kingdom. The royal houses are not recognised by the government of Indonesia; however, they originated before Dutch colonisation.