According to this map from Hyrule Historia, the Era of Decline starts with the tragedy of princess Zelda 1. Zeldafan1982 (talk)
Hyrule Historia reference
Encyclopedia doesn't mention that the Era of Decline starts from and includes the tragedy of Princess Zelda 1. Therefore, I think that the HH reference should be added. Zeldafan1982 (talk) 15:12, 2 April 2020 (UTC)