Istari appear in Middle-earth
Event Type: General
Age: 3rd Age - The Kings
"When maybe a thousand years had passed, and the first shadow had fallen on Greenwood the Great, the Istari or Wizards appeared in Middle-earth. It was afterwards said that they came out of the Far West and were messengers sent to contest the power of Sauron, and to unite all those who had the will to resist him; but they were forbidden to match his power with power, or to seek to dominate Elves and Men by force or fear."
RotK, Appendix B, The Tale of Years
"They first appeared in Middle-earth about the year 1000 of the Third Age, but for long they went about in simple guise, as it were of Men already old in years but hale in body, travellers and wanderers, gaining knowledge of Middle-earth and all that dwelt therein, but revealing to none their powers and purposes. In that time Men saw them seldom and heeded them little. But as the shadow of Sauron began to grow and take shape again, they became more active and sought ever to contest the growth of the Shadow, and to move Elves and Men to beware of their peril....
Emissaries they were from Lords of the West, the Valar, who still took counsel for the governance of Middle-earth, and when the shadow of Sauron began first to stir again took this means of resisting him. For with the consent of Eru they sent members of their own high order, but clad in bodies of as of Men, real and not feigned, but subject to the fears and pains and weariness of earth, able to hunger and thirst and be slain; though because of their noble spirits they did not die, and aged only by the cares and labours of many long years. And this the Valar did, desiring to amend the errors of old, especially that they had attempted to guard and seclude the Eldar by their own might and glory fully revealed; whereas now their emissaries were forbidden to reveal themselves in forms of majesty, or to seek to rule the wills of Men and Elves by open display of power, but coming in shapes weak and humble were bidden to advise and persuade Men and Elves to good, and to seek to unite in love and understanding all those whom Sauron, should he come again, would endeavour to dominate and corrupt."
Unfinished Tales, Part 4, III, The Istari