AHC: Most powerful,advanced and largest possible Zoroastrian Persia

[Albert.Nik]

With a POD anywhere starting from Medes and the Indo-Iranian migrations(including Indo-Aryans),make a very strong Zoroastrian(or any common Indo-Iranian monotheism) Persian/Iranian empire with a large population,more advanced infrastructure,a larger territory,etc. The largest possible spread of such an empire can range from Egypt to Upper Gangetic Plains.
Have PODs like
*More expansion oriented Iranian Empire with settlements built in Bactria,Sindh,Punjab,Upper Gangetic plains,Yemen and if possible in Levant and Egypt as the Romans did.
*Indo-Iranians and Indo-Aryans are more closely related instead of branching out which happened around 1600BC.
*An unusually strong and unified Empire within their homeland(Western Anatolia,Iran and Transoxania) and then begin expansion outward.

 

[Philip]

Heralcius falls off his horse in 610 or there-abouts. The war ends by 615. The Sassanians consolidate their hold on Syria, Egypt, and Armenia. They avoid civil war and are able to contain/absorb the Arab expansion. Much rejoicing and world domination ensues.

 

[Arkenfolm]

No Islam plus a Zoroastrian version of Nader Shah would do it. These alt-Afsharids would unlike OTL consolidate their realm and modernize Tanzimat-style, inviting foreign investment from Europe/China. They'd deal with surplus population by pushing into Central Asia and subduing the locals like Russia did while settling more Persians there, meanwhile they'd have a number of vassal states all the way to Delhi (the Indus would mark the southern border) plus in Arabia. If they don't have Syria (difficult to assimilate, regional Aramaic nationalism) and thus an outlet to the Mediterranean, Georgia would be easier to conquer (for Black Sea outlet) since the population is smaller (albeit whoever rules Anatolia would have something to say about that). Culturally they'd enforce a standard language on their empire early on, maybe accompanied by a reform of the Pahlavi script which is very difficult and ambiguous--this should erode regionalism (Kurds, Pashtuns, non-Persian speakers, etc.) although not entirely. Economy would be driven extensively by oil and mineral wealth, but agriculture should be powerful as well. The 5,000+ year old tradition of waterworks should continue, with a Caspian-Aral canal to prevent the Aral from drying up and a Caspian-Indian canal (Iranrud)--both proposed routes, one east one west, since it makes a good defensive line. Ideal capital is Esfahan since it's centrally located and out of the main earthquake zone (modern Iran has considered moving from Tehran to Esfahan for this reason).

I'd compare this Persia to the Russian Empire in many ways, albeit it has a lower potential population (although it's still easily 250 million plus). Easily a great power with a similar economy to Russia (which could have problems at times, granted). With Abadan, the Persian Gulf, and Baku, they'd have the largest (and oldest) sources of oil in the Old World from the 19th to mid-20th centuries.

 

[Frrf]

Xerxes is successful in Greece and the Achaemenid Empire consolidates enough that a coherant identity and ideology forms, like in China, that can survive civil wars, changes in dynasty and occasional periods of disunity. Comprising as its core the Iranian plateau, Mesopotamia, Syria/the Levant, Transoxiania and Anatolia, with occasional possesions in Egypt and beyond the Hindu Kush, this Imperial state could well develop as the core and crossworld of the old world, wealthy beyond measure and meeting point for philosophies and scientific theories from India, Europe, North Africa and China. Given the distinct absence of a proselytising drive in Zoroastrianism, it'd probably remain confined to ethnic Persians and the Imperial court, but much like Chinese traditional religion, at least the façade of the faith could well be expected, almost required of Shahanshahs.