By Water 5: Full Circle

Ashmara Alahin accompanies a Thanian-Karian expedition across barren, barbarian-infested deserts and desolate, poisonous mountains, before finally arriving at the western coasts of the Old World.
There they make a discovery which will change everyone's view of their world. During the gruelling return journey, the expedition's leader dies and barbarians seek to take advantage of the weakness of the travellers.
But the return to Thania is problematic for some and when Ashmara returns to the New World with amazing news, for both Rako and her, she is too late to avert tragedy. Unable to discover what happened to her father, she is constrained by tragic events, settling for what she can do, rather than what she desired. But good fortune arrives and new possibilities open for others in the family of Rakvir and Arhilka Stagarnik.
The fifth and final volume in the epic "By Water" is set in a distant planet, not too dissimilar from our own, written by Richard Hernaman Allen.