The Sulu Archipelago (Tausug: سُوگْ, Jawi: , ) is a chain of islands in the Pacific Ocean, in the southwestern Philippines. The archipelago forms the northern limit of the Celebes Sea and southern limit of the Sulu Sea. The Sulu Archipelago islands are within the Mindanao island group, consisting of the provinces of Basilan, Sulu, and Tawi-Tawi; hence the archipelago is sometimes referred to as Basulta, derived from the first syllables of the three provinces. The archipelago is not, as is often supposed, the remains of a land bridge between Borneo and the Philippines. Rather, it is the exposed edge of small submarine ridges produced by tectonic tilting of the sea bottom. Basilan, Jolo, Tawitawi and other islands in the group are extinct volcanic cones rising from the southernmost ridge. Tawi-Tawi, the southernmost island of the group, has a serpentine basement-complex core with a limestone covering. This island chain is an important migration route for birds. The largest municipalities in the area are on the island of Jolo. The larger island of Palawan to its north, the coastal regions of the westward-extending Zamboanga Peninsula of Mindanao, and the north-eastern part of the island of Borneo were formerly parts of the thalassocratic Sultanate of Sulu. The archipelago is the home of the indigenous Tausug people; various group of Samal (or Sama) people including the semi-nomadic Badjaw; the land-based Sama; the related Yakan people; and the Jama Mapun people. The Tausug language is spoken widely in the Sulu Archipelago as both first and second languages throughout these islands. The Yakan language is spoken mainly in Basilan Island. Numerous dialects of Sinama are spoken throughout the archipelago, from the Tawi-Tawi Island group, to the Mapun island group (Mapun), to the coast of Mindanao and beyond. Geography The archipelago is geographically subdivided into several groups, most significantly those around the main islands Basilan, Jolo and Tawi-Tawi. There are, however, other groups containing mostly small islands; not all of these are inhabited: Basilan group Basilan Pilas Jolo group Capual Jolo island Pata Tongquil Keenapusan group Laparan group Deatoboato Cap Island Laparan Dog Can Pearl Bank (atoll) Pangutaran group Kulasssein Panducan Pangutaran Sibutu group Andulinang Mardanas Omapoy Panguan Sibutu Sitangkai Tapul group Lapac Lugus (Bulipongpong) Siasi Tapul Tawi-Tawi group Bongao Manuk Mankaw Simunul Sanga-Sanga Tawitawi Topaan Others/Outliers Mapun (formerly Cagayan de Tawi-Tawi/Cagayan de Sulu) Turtle Islands History The Sulu Archipelago was once part of Majapahit Empire