 Slave-raids into the island's interior likewise commenced.As these raids became more and more frequent, the native Yakans retreated farther and farther inland, away from the coasts which were periodically harried by Datu Bantilan's Tausug warriors and slave-raiders.The biggest and most advanced Yakan coastal settlement was located on the northeastern shores of Basilan, in Lamitan, and far from the usual routes of pirate raiders on their way to Zamboanga from Sulu and Maluso.