From the above-mentioned marriage alliances came the Moro dynasties of Maguindanao, Buayan, and Butig. From the Maranaos of Butig, Islam was then introduced to the Maranaos of Lake Lanao. Whereas the base and strength of the Buayan sultanate was in the upper valley of the Pulangi in the interior of eastern Mindanao, that of the sultanate of Maguindanao was at the lower valley and the nearby coastal areas. Actually, for many years it was Iranun support that strengthened the Maguindanaon rulers against their antagonists. (Majul, 1973)