Wall of Power
The Wall of Power was a magical green barrier which spanned the northern reaches of Sapience for centuries. It was devised by the Tsol'dasi and maintained via the Two Trees of Istarion to separate the northern reaches from the rest of the continent. Thus isolated, the Tsol'dasi hoped that they would never again be involved in the affairs of humankind.
Centuries passed, and the wall's borders gradually shifted, changing with time as the energies that sustained it flowed elsewhere. The first change was noted in the year 311 AF, the shift revealing areas such as Aran'riod, Kamleikan, and features of the Ishana Peninsula. The barrier retreated further in 409 AF, leading to the discovery of the ruins of Morindar, and yet again in 413 AF, revealing the city of Isaia. In 552 AF, it dissolved completely, exposing the continent of Sapience in its entirety for the first time in the Modern Age.