Early in the Medieval era, Kedah became part of Srivijaya (a major power in the Indian Ocean trade). This led to rivalries with the Indian states, especially the Chola Empire from the 9th to 13th centuries CE. The Cholas had a powerful merchant and naval fleet in the Indian Ocean and the Bay of Bengal. In the early 11th century, Tamil Chola King Rajendra Chola I sent an expedition to attack Kedah (Sri Vijaya) on behalf of one of its rulers who sought his assistance to gain the throne.The Chola fleets successfully defeated the Srivijaya empire, captured and sacked Kedah.