Early in southern Thailand's recorded history, starting in the seventh century, the Hindu trading empire of Srivijaya, based in southern Sumatra (part of present-day Indonesia), controlled its waters; both Indian and Chinese ships sailed through them. After the decline of Srivijaya's influence, in the 13th century, Muslim sultanates, many of which were based in what is now Malaysia, rose to power. Their authority was shared with the Buddhist city-state of Nakhon Si Thammarat, located on the eastern coast, which developed around the same time. Today, most of the residents of the southernmost provinces—Narathiwat, Pattani, Songkhla, and Yala—are Muslim, and many of them, citing discrimination born of centuries of political and cultural domination by northern Thais, have separatist leanings. The politically charged atmosphere has frequently led to violence. However, in the provinces just to the north—including Phatthalung, Trang, and the popular beach resort destinations of Krabi and Phuket—the population is mostly Buddhist, and the area has remained largely peaceful.