Good economy can impact immigration.
10,000 deaths a day from plague impacts immigration far more.
(I realize that 10k/day is most definitely exaggeration)
Good economy can impact immigration.
Constantinople WAS the largest city in OTL - repeatedly. In 5th-6th century, and again in 16th-17th century.Ancient PODs aren't going to cut it. In order for Constantinople to become the largest city in the world it needs to be the focal point of a large stable state which will give it a large population to move to the city when industrialization and urbanization take hold.
Or successful Ottoman reforms butterfly away WWI in the first place.You could probably get it with earlier Ottoman reforms, some more Ottoman successes on various fronts (they might have to hold onto Egypt but it might not be an absolute requirement) and Ottoman neutrality in WWI (or possibly even Central Power victory in WWI since you likely need a strong Hapsburg Empire or similar state in the region as well).
Constantinople WAS the largest city in OTL - repeatedly. In 5th-6th century, and again in 16th-17th century.
It is the other part of original condition. At least 1 million more than the second largest city. Which means at least 1,5...2,5 million people (second largest would be at least 0,5 millions). No city exceeded 1,5 millions before 1800, and OTL the first city to exceed the second city by 1 million was London, by 1850. The 2nd place was shared then by Paris and Edo.
They certainly were Europe's largest city for some time, after Rome declined. How big were the East Asian cities at that time? Are there any data?
Quite hard to find reliable ones.
Serious candidates:
Ctesiphon
Pataliputra
Luoyang
Nanjing