the Dallero river tribes

To the north-east of Castaponda, where lake Pekkale births the Dallero river, around the Forest of Dreams, there are seven tribes. Three of them, residing between the Coerre sea and the Forest, are peaceful people, who worship the Dreams and commune with the spirits. The three between the Forest and the river fear the Forest, never approach it, and have a passionate hate for everything to do with the Dreams and the spirits. The one between the Forest and the Siccoreo river is neutral. They neither worship nor fear the Forest, and prefer to deal with outsiders than the other tribes.
Buccaha, Lundo and Trasc are the river tribes, and together one of the most warlike cultures in the entirety of Eam'Rel. Their way of life is frugal; they hunt, they compete, they eat with no spices and drink rarely wine. The society's hierarchy is very simple: the best warriors become commanders, and eventually leaders to one of the tribes. It doesn't matter whose son or daughter you are, so long as you can wield a sword or a bow, you're worthy.
The Buccaha tribe, who live closest to the lake, are the most brutal of the three. When a baby is born, they carry it to the lake and dip it in the always cold water. If the child survives, the lake has blessed it. If it dies, the lake has claimed it, and they spill its blood in the water, so the sacrifice will go back to the earth and make the harvest strong. Almost half of the children born to the Buccaha die in the waters, but the ones who survive never fall ill in their lives. The Buccaha would rather die than become limp or incompetent, and in their many conflicts with the other tribes, the wounded are those who fight the hardest, that throw themselves with savage determination to their enemies, in order to take as many with them before they die wielding a sword. There are neither healers nor herbalists among the Buccaha. You live or die, and if you become unable to fight, you go to the lake and give your blood to the water.