with a pod after 1500 is it realistic and possible for Iran (Persia) to get a colonial empire?
Extra points for a Persian settler colony in australia
Also extra points for a pod late enough in time so that it’s still possible for Reza shah to rise to power.
Absolutely Persia can get colonies. It's harder for them to get a settler colony though, due to the under-population of the heartland.
Maybe if you figure out a PoD that gives Iran a stronger population base? For example, if the population decline at the end of the Safavid period was avoided. But that's hard because we don't really know what caused that (probably cholera, but it's not certain).
Do they have to be overseas colonies? Because if not I could sea Persia colonizing Central Asia in the absence of Russia.
Well, they did. Persians are still a major people in the area today (Persians are called Tajiks in central asia). They were pushed back by the steppe peoples.
And a port in Basra would easily connect to and facilitate the commerce of the Persian heartland... how exactly? The Zargos are just as much of an obstacle unless you move the center of the Empire to Khuzestan/Mesopotamia, which makes holding the majority of the nation you just left highly difficult as well as making the state highly vulnerable by removing it's protective geography and isolating themselves from the tribal populations that provide the core of your military might in the form of light cavalry.
Persia had been a naval power often enough in the past. Post 1500 it had 2 issues - 1) the timber came from the mountains around the Caspian sea - obviously too far away to transport cheaply to the Persian Gulf; 2) they lacked Mesopotamia, which was the real heart of the empire (if not the heart of the Persian nation).
So at minimum, Persia needs some ports with good timber nearby. For bonus points, it needs Mesopotamia. For maximum colonial potential, you need to replace the population crash in the 18th Century with population growth.
Probably the easiest way to do this is if Persia conquers the West coast of India, which had a strong naval tradition, a supply of timber, and was producing naval officers who could trounce Europeans. With that it's logical that Persia would seek to again dominate Oman, which would motivate Persia to get involved on the Swahili coast of Africa (which they'd been involved in before).
That's all something that might have happened if Nader Shah had set up an enduring regime, meaning that Persia is strong at a time when the Portuguese, Ottomans and Mughals are weakening and the British haven't gotten strong momentum yet.
And in such a scenario, Persia might then get drawn further into Africa, much as Egypt did, as the scramble for Africa gets going.
fasquardon