The Arbin River is fed mostly by rainwater, caused by clouds that form over the Arbin Mountains. There are several tributaries that originate in the mountains northwest of the official start, but those only account for 4% of the total water capacity. All of these tributaries group up and flow in between two mountains, called Tiunavir and Dranovir, who signal the beginning of the actual Arbin River. From there it follows the gaps in the mountains, all the way to the coastline. Because the mountains are quite packed together, the average width of the river is only about 4 meters and the average depth is 4 meters.
Moriv, however, is fed mostly by the Etorma spring, which is hidden deep in the mountains. Because the mountains are not as tall there, they cannot generate enough clouds to sustain the river by themselves. This spring is regarded as the official start of the Moriv River, and to reduce contamination, access to the spring has been restricted to the general public. As it moves away from the spring, the Moriv River will separate into two, three, or even four subrivers before joining back together later. This is due to the region's considerably low mountains, whose shallow bases feature little-to-no height difference on either side. The river's average width is 6 meters, and its average depth is 1 meter.
The Pero River features some of the most varied mountains on the planet, and it is quite common to see peaks right next to each other with up to a 5,000 m difference. It is due to this variation that the Pero River is extremely jagged and winding, and those that sail down this river often do so acknowledging the high risk of crashes and capsizes.
The Arbin Mountains form a cradle around the Rivers, and serve to shape, nurture, and protect them. They are the result of hundreds of millennia of tectonic movement around a geological area called the Arbin Fault System, where the Oragonian, Lotaoian, Nekarian and Varonian plates all push into the tiny Arbin Plate, squishing it from all sides and forming the complex nature of this Watershed. In a few million years, this continued movement will cause the mountains to thicken, which in turn will thin the Rivers and cause them to be completely filled up by the Mountains. This will also completely cut off the Tayzem Region from the Blivonic Valley, restricting any travel between the two regions exclusively to sea.