Java and Bali
Six centuries of Hindu-Buddhist kingship on one island's rice, from the Brantas valley through Majapahit's own thalassocracy — plus the western kingdom that was never part of it, and the Balinese court that kept the old religion after Java itself turned Muslim.
The line below is a time axis. Position on it is date, so concurrency is visible: concurrent polities sit side by side rather than in sequence.
3 sourced edges run between this region and another, to Srivijaya, The Sultanate of Demak and The Sultanate of Banten. Those are not drawn on this line — a thread that crossed regions would assert a sequence nobody cited — but they are on each polity’s own page.