Elves left for Valinor because they were disturbed by the recent war. However, Elven kingdoms still survived in Lindon, Lothlórien, and Mirkwood. Rivendell also became a prominent haven for the Elves and other races. Throughout the Age, they chose not to mingle much in the matters of other lands, and only came to the aid of other races in time of war. The Elves devoted themselves to artistic pleasures, and tended to the lands which they occupied. The gradual decline of Elven populations occurred throughout the Age as the rise of Sauron came to dominate Middle-earth. By the end of the Third Age, only fragments of the once-grand Elven civilization survived in Middle-earth. The Wizards arrived around a thousand years after the start of this period to aid the Free Peoples, most importantly Gandalf and Saruman. The One Ring was found by Sméagol but, under the power of the Ring and ignorant of its true nature, he retreated with the Ring to a secret life under the Misty Mountains. Middle-earth's devastating Great Plague originated in its vast eastern region, Rhûn, where it caused considerable suffering. By the winter of late the Plague spread from Rhûn into Wilderland, on the east of Middle-earth's western lands; in Wilderland it killed more than half the population. In the following year the Great Plague spread into Gondor and then Eriador. In Gondor the Plague caused many deaths, including king Telemnar, his children, and the White Tree; the population of the capital city Osgiliath was decimated, and government of the kingdom was transferred to Minas Tirith. In Eriador, the nascent Hobbit-realm of the Shire suffered "great loss" in what they called the Dark Plague. The so-called Watchful Peace began in , when Gandalf went to Dol Guldur and the evil dwelling there (later known to be Sauron) fled to the far east. It lasted until , when Sauron returned with new strength. During this period Gondor strengthened its borders, keeping a watchful eye on the east, as Minas Morgul was still a threat on their flank and Mordor was still occupied with Orcs. There were minor skirmishes with Umbar. In the north, Arnor was long gone, but the Hobbits of the Shire prospered, getting their first Took Thain, and colonizing Buckland. The Dwarves of Durin's folk under Thorin I abandoned Erebor, and left for the Grey Mountains, where most of their kin now gathered. Meanwhile,