The Sultanate of Mataram () was the last major independent Javanese kingdom on the island of Java before it was colonised by the Dutch. It was the dominant political force radiating from the interior of Central Java from the late 16th century until the beginning of the 18th century. Mataram reached its peak of power during the reign of Sultan Agung Anyokrokusumo (), and began to decline after his death in 1645. By the mid-18th century, Mataram lost both power and territory to the Dutch East India Company (Dutch: Vereenigde Oost-Indische Compagnie; VOC). It had become a vassal state of the company by 1749. Etymology The name Mataram itself was never the official name of any polity, as the Javanese often refer to their realm simply as Bhumi Jawa or Tanah Jawi ("Land of Java"). Mataram refers to the historical areas of plains south of Mount Merapi around present-day Muntilan, Sleman, Yogyakarta, and Prambanan. More precisely, it refers to the Kota Gede area, the capital of the Sultanate on the outskirts of southern Yogyakarta. A common practice in Java is to refer to their kingdom by metonymy, specifically by the location of its capital. Historically, there were two kingdoms that have existed in this region and both are called Mataram. The later kingdom, however, is often called Mataram Islam or "Mataram Sultanate" to distinguish it from the Hindu-Buddhist 9th-century Kingdom of Mataram. Historiography The key sources to uncover the history of the Mataram Sultanate are local Javanese historical accounts called Babad, and Dutch accounts by the Dutch East India Company (VOC). The problems with traditional Javanese Babad, are that they are often undated, obscure and incorporate non-historic, mythological and fantastic elements because these Javanese historical accounts were used as a tool to legitimize the authority of the ruler. An example of a mythical element is the sacred bonds between Panembahan Senapati with mythical Ratu Kidul, the ruler of Java's Southern Seas as his spiritual consort, as claimed in the Babad Tanah Jawi. The dates for events before the Siege of Batavia during the reign of Sultan Agung, the third king of Mataram, are difficult to determine. There are several annals used by H.J. de Graaf in his histories such as Babad Sangkala and Babad Momana which contain list of events and dates from the Javanese calendar (A.J., Anno Javanicus), but besides de Graaf's questionable practice of simply adding 78 to