While the ami soul is related to breath, the suns soul is tied to water.
Waterways are passages for travel for the suns souls, especially the World
River which enters the middle world by the World Tree in the south then
flows into the lower world in the north. Of course this belief would seem
natural because the great waterways of North Asia all feed into the Arctic
Ocean Like the constantly renewing flow of water in these great rivers,
suns souls return to the earth again and again. A model has been developed
out of the various myths explaining this process which exist throughout
Siberia. According to this model, souls enter the world through the source
of the World River by the World Tree, where Umai stands watch over the ami
souls. At the time of birth, the reincarnating souls come down the river
and enter the infant at the time of birth. At death, the suns travels down
the river to the Arctic Ocean and the entrance to the lower world while the
ami takes the form of a bird and flies back to the World Tree. In order to
return to this world the suns will either travel underground to the World
River’s source or travel along the Milky Way to the lands in the south
where the upper and middle worlds touch.

This cycle of life presents an interesting parallel to the water cycle,
which generations of native peoples could not have failed to understand to
some degree. Water falls on the earth as rain and flows from the ground at
springs (springs are considered a gateway to the lower world). It flows
ultimately into the ocean, where evaporation raises water once more to the
heavens so it can fall on earth again as rain. In the same way, human souls
follow the World River to the sea, only once more to emerge at its source
in order to incarnate once more.