Unicorn Run
The Unicorn Run was a river that started somewhere in the Star Mounts and joined the River Delimbiyr near Secomber. Bards and sages passed down the tale that the headwaters of the Unicorn Run were, in truth, the Font of Life, and a cradle of fecundity. Each natural race was said to have emerged from the womb of Chauntea onto Toril at the river's source, and then traveled down the Unicorn Run to the outside world. Some said that a daughter of Chauntea resided at the river's source to usher the newborns into the world, while others claimed that Shiallia midwifed the process.
Regardless of the truth, the elves, korreds, and halflings all agreed that the Unicorn Run was sacred to life and a site of incredible purity. As a result, all three races had strong taboos about extended trips up the run, for if the river was ever fouled, then no new races would ever be born on Toril again.