The Hindu Majapahit kingdom expanded across the Sunda Strait, while Islamic influences, including the traveler Ibn Battuta, arrived from the north, around the Strait of Malacca.  
Its largest lake, Lake Toba, was created by a massive volcanic eruption 75,000 years ago. This island's natural resources include the oilfields of Riau province and tobacco, tea, and rubber plantations in the Deli and Medan areas of the northeast.  It was dominated in the 7th through 9th centuries by the Mahayana Buddhist kingdom of Srivijaya, whose capital of Palembang was sacked by Tamil traders from Cola. The Hindu Majapahit kingdom expanded across the Sunda Strait, while Islamic influences, including the traveler Ibn Battuta, arrived from the north, around the Strait of Malacca.  FTP, name this Indonesian island, home to the separatist movement of Aceh and, according to Arthur Conan Doyle, a giant rat.
Its largest lake, Lake Toba, was created by a massive volcanic eruption 75,000 years ago.
Sumatra