Some 4,200 years ago, people started to leave what is now Taiwan to migrate to the thousands of islands to the south, spanning as far west as Madagascar in the western Indian Ocean and as far east as Rapa Nui (Easter Island) in the eastern Pacific Ocean.

We can trace this migration through the way language spread, creating the largest-scale language dispersal in prehistory.

But what exactly drove these people to make these distant and dangerous voyages? Our discovery of a 4,000-year-old painting of a sunburst in southeastern Indonesia offers some clues.

A charismatic cultural identity

Austronesian is a close-knit language family spoken across much of Malaysia, the Philippines, Indonesia, Madagascar and the Pacific Islands. Some of the major languages in this family include Malay, Javanese, Sundanese, Tagalog, Cebuano and Malagasy.

We know the Austronesian migration began at least around 4,200 years ago, as this is when characteristic Austronesian red pottery and rectangular stone adzes (axe-like tools) appear on islands south of Taiwan.

The extraordinary seafaring abilities of Austronesians were underpinned by the outrigger canoe, but it is unclear which other factors propelled their expansion.

Previous models have suggested advancements in rice farming and storage (thanks to pottery) might have fuelled population growth, prompting the........

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