The Pacific holds the longest deliberate maritime expansion in human history, and the religious dimension of it is not incidental.
Over roughly two thousand years, Austronesian-speaking voyagers settled island groups across a third of the earth's surface, sailing against prevailing winds in double-hulled canoes, without instruments, navigating by star paths, swell patterns, cloud formations and the behaviour of birds. Patrick Kirch's synthesis of the archaeology sets out the sequence and the pauses in it, and makes clear how much of the movement was purposeful settlement rather than accident.
The knowledge that made it possible was held as sacred property. Navigators were trained in schools, initiated, and bound by restrictions; the knowledge belonged to particular lineages and was not general. Canoes were built under ritual constraint and launched with ceremony, and the founding of a new settlement typically involved carrying a stone from an established ceremonial ground to establish a new one, which made expansion a religious act as well as a demographic one.
What travelled with the canoes is visible in the shared inheritance across the region: related names for the same gods, genealogy as the form in which sacred claims are made, and the paired concepts of mana and tapu. By the time Europeans arrived, related religious systems were in use across thousands of miles of open ocean, which was itself taken as evidence of a common origin long before archaeology could demonstrate one.