Glan Hinterlands were sparsely populated by native highlanders, particularly, B'laans, Manobos, Bagobos, Tagacaolos and Tagabelles. The coast was occupied by Sangils. It was during the coming of the early Chinese and Arab traders that Sarangani shore became a trading port. The coast was frequented by sea pirates who brought along looted treasures. In the late 14th century, Muslim missionaries arrived in the area and introduced Islam. The Sangils were the first converts to Islam Faith in Sarangani This explains the claim of historians placing this coastline inhabitants of the bay in the list of thirteen tribes of Muslim Filipinos.
The King of Spain sent four expeditions to the Philippines after the death of Magellan. The first three expeditions led by Garcia Jofre de Loisa in 1525, Sebastian Cabot in 1526, Alvaro de Saavedra in 1527 had all met their dismal end. The fourth expedition headed by Ruy Lopez de Villalobos reached Mindanao and drifted towards Sarangani Bay:
"It reached the Island on February 2, 1543 and named the place Mindanao: Caesarea Caroli in honor of King Charles I (Emperor Charles V). By sailing along Sarangani Bay, in search of provisions, Villalobos fortuitously baptized the whole archipelago: Islas Filipinas: Philippine Islands, in honor of Prince Philip of Asturias, who became King Philip II."
(History of the Philippines: A Focus on the Christianization of Bohol 1521-1991: Fr.Josemaria S. Luengo, PhD, pp 35-36)
This account strengthens Sarangani's own share of that glorious past - an untold part of the Philippine History which Glan can now lay claim as it positioned in the mouth of the bay.