The Rain Wilds are a large, marshy territory southwest of Chalced on The Cursed Shores, claimed by both Chalced and Jamaillia. The land is dominated by the Rain Wild River, a long and twisting river with countless territories and varying depth. It has two major settlements, Bingtown and Trehaug.
In ancient times the land was primarily rolling meadows of fertile ground, which hosted grain fields and well-tended livestock. Enormous Elderling cities played host to Dragons and the populace centered around the Serpent River. The volcanic cataclysm that killed off both the dragons and the Elderlings also disrupted the flow of the river, leaving the shallower Rain Wild River behind and turning the land into marshes.
Much of the inland Rain Wilds remained unmapped until the expedition of the Tarman, as the river's path frequently changes and the lack of arable land prevents settlement. The Tarman expedition was the first to chart much of the Rain Wild River and surrounding land upstream of the settlement of Cassarick.
In the north, the Great Blue Lake is noticeably free of the high acidity of the river system, suggesting that the source of the acidity is from a downstream tributary.
Numerous Elderling settlements existed along the river, which hosted dragons and provided food, shelter, heat, and Silver to them. The dragon life cycle was disrupted by a cataclysmic event which buried several Elderling cities, destroyed multiple cocooning grounds, and altered the course of the river permanently.
The landscape underwent dramatic change, with most of the surrounding land becoming too marshy and soft to support agriculture or livestock. Modern Rain Wild cities are not built on the soft ground, but in trees.
The fauna and flora of The Rain Wilds is highly diverse and heterogenous. Many inland species have never been properly identified or recorded. Many of the creatures within The Rain Wilds are predatory, dangerous or parasitic.
The botany is dominated by trees, which are able to grow to immense size in the marshy soil along the riverbanks. These trees form a dense canopy that prevents most sunlight from penetrating. Despite the lack of sunlight, there exists a dense underbrush on the forest floor, making travel over land difficult. A variety of grasses and reeds grow directly along the banks of the river. A large number of mosses and vines grow in the Rain Wilds, including the floral skymaw and the edible bread leaf vine.
Historically, the top species of the Rain Wilds is the dragon. The Rain Wild River is an essential part of the dragon life cycle, as it is the route by which serpents migrate to their cocooning grounds. The magical influence of the dragons is still present in the Rain Wilds and can be seen in the humans who settle or are born there.
Other noteworthy reptile species include the parasitic rasp snake and the venemous gallator.
The Rain Wild River is the habitat for many kinds of fish, including flatfish and a red-bellied fish favored by dragons despite being poisonous to humans.
Weather in the Rain Wilds is predictable. The spring and summer months are warm, but little sunlight reaches the ground through the canopy. Rain is nearly constant in the autumn and winter months. The river is prone to frequent, unpredictable flooding. The area also experiences frequent earthquakes, which have a pronounced effect on the river's flow and chemical composition.
Rain Wild Traders discovered the buried Elderling city Frengong and built the new settlement of Trehaug above it. Excavating the Frengong ruins and selling the discovered artifacts to the outside world ensured the survival of the city, which had little other wealth of its own.
One of the most important discoveries in Frengong was that of wizardwood logs, which the Traders used to create liveships. With liveships, trade could continue between Bingtown and Trehaug uninterrupted.
The lingering effects of the ancient dragon population has had lingering effects on the Rain Wild populations. Those who live in the Rain Wilds have shortened life expectancy, poor health, and high rates of miscarriage and stillbirth. As they age, they experience physical changes, including uncontrolled skin growths, skin texture changes, and changes in eye color. Occasionally children born in the Rain Wilds are born with these or other features, such as claws instead of nails. The life expectancy for these children is so poor that they are often left to die shortly after birth.
Until the discovery of Kelsingra by the Tarman expedition, little was known about the Rain Wilds inland and upriver of Rain Wild Trader settlements.