Ithilien mostly deserted due to attacks by Uruks of Mordor
Event Type: Cultural/Social
Age: 3rd Age - The Stewards
2901 Most of the remaining inhabitants of Ithilien desert it owing to the attacks of Uruks of Mordor. The secret refuge of Henneth Annûn is built.
The Return of the King, LoTR Appendix B, The Tale of Years: The Third Age
All but the hardiest of its people deserted Ithilien and removed west over Anduin, for the land was infested by Mordor-orcs.
The Return of the King, LoTR Appendix A, Annals of the Kings and Rulers: Gondor and the Heirs of Anárion: The Stewards
Túrin II […] In his time [folk finally fled >] many more folk removed west over Anduin from Ithilien, which became wild and infested by Mordor-orcs.
The Peoples of Middle-Earth, HoME Vol 12, Part 1, Ch 7, The Heirs of Elendil: The Ruling Stewards of Gondor