I've been listening to a couple of Patrick Wyman's Tides of History podcast episodes about the archaeological, linguistic and genetic evidence on migration across Oceania by Austronesian speaking people around 4-3kya. One thing I've long wondered about which he doesn't touch on (perhaps because little or nothing is known) is the mythology that led family groups to undertake voyages that, I assume, most did not survive. Heading out on 1000 km voyages across open ocean carrying all your water (& food?) without knowing what's over the horizon seems likely to end badly for all but a rare lucky few.
The descendants of a group that did make it would, however - one imagines - maintain a tradition that glorified what their ancestors had done, leading to elevation of the idea in later generations. Is anything known about these stories & the legends they became?
ETA: Found some interesting discussion here about "founder ideology" though it's pretty speculative.