Thanks for the thread. Well there is some addition that I would want to say. First is that Sumatra and Java are the two main islands that shape Indonesian history just like have been seen on the story. Sumatran people not only make the first big kingdom in Indonesia which is Srivijaya but later also build the first Islamic Sultanates. Islam was first flourist in Sumatra as the region is near busy sea trading route of Malacca Strait, later Islam is spread into another region like Kalimantan and Java and help decrease Majapahit territory where in the end whole region in Western Indonesia become fully Islamic in the exception of Bali island.
There is recent video made by CNA (Singapore TV media) about Majapahit that you are maybe interested on it.