Sumbawa had , historically speaking , three major linguistic groups who spoke languages that were unintelligible to each other . One group centered in the western side of the island speaks Basa Semawa ( Indonesian : '' Bahasa Sumbawa '' ) which is similar to the Sasak language from Lombok ; the second group in the east speaks Nggahi Mbojo ( '' Bahasa Bima '' ) . They were once separated by the Tambora culture , which spoke a language related to neither . After the demise of Tambora due to the 1815 eruption , local kingdoms based in Sumbawa Besar and Bima became the two focal points of Sumbawa . This division of the island into two parts remains today ; Sumbawa Besar and Bima are the two largest towns on the island , and are the centers of distinct cultural groups that share the island
1815 eruption
1815 eruption of Mount Tambora
Sumbawa