Maguindanaon means "people of the flood plain" for they mainly inhabit the broad Pulangi River valley and delta which occasionally flood. The Pulangi River has its beginning in the mountains from the Liguasan Marsh and Lake Buluan. Because the authority and influence of Maguindanaon rulers formerly extended over a wide territory from Sibugay Bay in the west to the coasts of Davao in the East, the name Mindanao was applied to the second largest island of the Philippines. They are found mainly in four provinces: Maguindanao, North Cotabato, South Cotabato, Sultan Kudarat, forming the Cotabato region.
The Maguindanaon are subdivided into two principal groups, each with its own dialect and traditional location: Tau-sa Ilud (people of the lower valley), and Tau-sa Laya (people of the upper valley). The Tau-sa Ilud are concentrated in the areas around Cotabato City and extend to South dinaig. They are primarily sedentary wet rice agriculturists. Traditionally, they constituted the Sultanate of Maguindanao based near present day Cotabato City. Their dialect is characterized by more rapid, "harder" consonant sounds, with preference for using "d" rather than "r" and variations on the use of "l" and "r".
The Tau-sa Laya are primarily concentrated in the areas of Datu Piang and extend south to the areas, which include Buluan. They practice semi-sedentary agriculture and grow corn and upland rice. Traditionally, they constitute the Rajahship of Buayan based near present-day town of Datu Piang. Their dialect is characterized by slower cadence, a drawl, with frequent omission of the consonants between vowels preference for using L rather than R, occasional variation of R for D and some differentiated vocabulary.