It takes about three weeks to move through Shadow to Yig using Pattern; hellriders can make the distance in three days if they don't get delayed by riding into some disaster. Yig roughly marks the boundary point at which the power of Amber fades and that of Chaos waxes. It is also believed to hold up the heavens in some manner or sense. Yig often seems different every time one visits it; it remains uncertain whether one is simply seeing different Shadows of Yig or the true Yig changes.
Some things, however, are constant. Yig is always a tree with a trunk a good half mile across that rises so high into the sky you cannot see its top. Tunnels sink into the earth around its roots, guarded by a serpent (not the Serpent of Chaos, but possibly a relative), while a flying unicorn defends its upper reaches. Yig always stands in the center of a great, barren patch of earth. It rains every afternoon.
And from the branches hangs a giant man, a good hundred feet tall or more. Sometimes he is being hung by the neck. Sometimes a rope or spear pierces him, holding him in place. Sometimes he is crucified. Sometimes the serpent bites his heel and the unicorn pierces his chest. Always his eyes are shut, he does not speak except to moan, and his face mixes agony and pleasure. Who he is or why he is there is unknown. Rumors say that whenever his tortures end, he will learn the secret of life. Other rumors claim enlightenment comes to those who hang from this tree. Some say Fuyutsuki hung himself from it to learn how to make the Pattern. (Fuyutsuki himself claims he found the instructions in a book called Pattern Making For Dummies). Prince Shizumaru is known to have hung from Yig to gain the Seed of Hope, and it is said that Prince Drake hung from Yig to learn how to make Werewindle.
Yig is defended by the Forestals, a group of potent druidical types who defend it from harm. They seem to be lead by a man named Forestal Troy.
Kanna has hunted down several Taylors who hoped to destroy Yig using weedkiller; the Black Heart Prophecy insinuates it could be destroyed using a Patternblade or a Logrusfoil.
Notable events at Yig in TAMD/UNS: