Islamic faith, introduced a more sophisticated political system. In Buayan, the transition to Islam took a longer time. Spanish chronicles was told that Buayan, and not Cotabato, was the most important settlement in Mindanao at that time. Spanish period In 1579, an expedition sent by Governor Francisco de Sande failed to conquer the Maguindanao. In 1596, the Spanish government gave Captain Estevan Rodriguez de Figueroa the sole right to colonize Mindanao. He met defeat in Buayan, and later, was killed in an ambush by a Buhahayen named Ubal. His forces retreated to an anchorage near Zamboanga. The rise of the Maguindanao-Cotabato power came after the defeat of Datu Sirongan of Buayan in 1606. From 1607 to 1635, new military alliances were formed, this time with Cotabato. By the 1630s, Cotabato had become a coastal power. In the early 17th century, the largest alliance composed of the Maguindanao, Maranao, Tausug, and other Muslim groups was formed by Sultan Kudarat or Cachel Corralat of Maguindanao, whose domain extended from the Davao Gulf to Dapitan on the Zamboanga Peninsula. Several expeditions sent by the Spanish authorities suffered defeat. In 1635, Captain Juan de Chaves occupied Zamboanga and erected a fort. This led to the defeat of Kudarat's feared admiral, Datu Tagal, who had raided pueblos in the Visayas. In 1637, Governor General Hurtado de Corcuera personally led an expedition against Kudarat, and triumphed over his forces at Lamitan and Ilian. Spanish presence was withdrawn in 1663, providing an opportunity for Kudarat to re consolidate his forces. From 1663 to 1718, Maguindanao influence extended as far as Zamboanga in the west, Cagayan de Oro in the north, Sarangani in the south, and Davao in the east. In 1719, the Spaniards reestablished control with the building of the strategic Fort Pilar in Zamboanga (Miravite 1976:40; Angeles 1974:28; Darangen 1980:42-45). The 1730s saw the weakening of the Maguindanao sultanate, as it struggled with civil war and internal disunity. Spanish help was sought by the besieged rajah mudah (crown prince), further destroying the prestige of the sultanate. Thus, Cotabato power became increasingly dependent on Spanish support. This deepening compromise with Spain led Cotabato to its downfall. Fearing Buayan's reemerging power, Sultan Kudarat II finally ceded Cotabato to Spain in return for an annual pension of 1,000 pesos for him, and 800 pesos for his son. Buayan, under Datu Uto, had, by the 1860s, become the power of