An enjoyable and well written fantasy adventure. The author has detailed and crunchy world building, neat mysteries to unravel, likeable and interesting characters, and a plot that ends nicely. It is not an absolutely amazing story, but it reliably does very well on just about everything you could want a fantasy adventure story to do.
The world building is a bit like Glorantha, in that you have farmers/hunters/gathers/herders who live in day to day contact with the mythic, with the minor gods and heroes of their land. A farmer might make a dozen prayers in a day, one to the goddess of the stream that goes through his land, one to the god of his pasture, one to the old great oak of the grove, etc. etc. And the minor gods of the land in turn play a key role in the success of his farming, and will talk with or advise or even inter-marry with the farmer and his family. This system is built out in a dozen different ways, and is combined with the different cultures the author has built up for his Viking/Native-American/Mongolian analogs. And as with Glorantha, in addition to these low tech-cultures and their godlings, there is a separate culture that is more advanced and organized and more populous, a Chinese-flavored city culture that worships a single monolithic River deity. And by river, we are talking along the lines of the Amazon. The River is enormously powerful and enormously hungry, and it swallows up and devours any godling that comes within reach of its waters. Fortunately, the River is also sleepy, and it has stayed within its banks for centuries.
So! That is at least the outlines of the world building. For the story, one thread follows a young princess of the River god's bloodline, as she tries to figure out why some members of her line disappear at puberty while others go on to be part of the ruling elite. The second thread is of a young barbarian cattle-man, who falls in love with a stream-god and vows to fight the River-God in her name. The two threads flow together until they finally intertwine at the ending. I liked it!