Isnt that a Zoroastrian sacred Bird?
Yes it dated back to ancient Iranian mythology and literature and also there is another Simurgh described in Iranian literature/mysticism ... ancient one is one wise bird which also mentioned in Shahnameh ..
Iran Simurgh SLV is named after this bird.
The second Simurgh that comes from our mysticism and postdated the first one is from
Speech of the Birds of Attar of Nishapuri and is symbol of "right" like the first one .. here Simurgh ain't one bird .. Simurgh as a word has a prefix and suffix : Si+Murgh .. Si means 30 in Farsi and Murgh is equal with bird which means 30 birds ... on other hand in Iran mysticism "bird" is considered and associated with "Self" and "Body" with "cage" ... which this bird(human\self) must break the cage (body) to get free and fly ...
In this story all birds gathered to find a king whom all must follow and submit they asked Hodhod (hoopoe) (wise bird in Iranian literature) and he guided them that there is a king by the name of Simurgh (king of all birds) (symbol of "right") who lives in Qaf mountain (Alborz mountain) so all birds decide to start this journey to find Simurgh , Hodhod (hoopoe) takes lead ..
They should pass 7 wadi\valley in order to get Simurgh:
1. Valley of the Quest, where the Wayfarer begins by casting aside all dogma, belief, and unbelief.
2. Valley of Love, where reason is abandoned for the sake of love.
3. Valley of Knowledge, where worldly knowledge becomes utterly useless.
4. Valley of Detachment, where all desires and attachments to the world are given up. Here, what is assumed to be “reality” vanishes.
5. Valley of Unity, where the Wayfarer realizes that everything is connected and that the Beloved is beyond everything, including harmony, multiplicity, and eternity.
6. Valley of Wonderment, where, entranced by the beauty of the Beloved, the Wayfarer becomes perplexed and, steeped in awe, finds that he or she has never known or understood anything.
7. Valley of Poverty and Annihilation, where the self disappears into the universe and the Wayfarer becomes timeless, existing in both the past and the future.
In such a long and tough journey many birds get tired and wouldn't continue and return but despite the problems 30 birds continue the journey and finally get to the Simurgh place ... but finally they realized that Simurgh is actually themselves 30 birds\Simurgh which turned to Simurgh ..