Originally Posted by
Legion_IX
Exactly this is not possible.
Baktra is the city with the highest cultural level of 50% of you starting cities. In my last game in turn 131 it was surrounded by baktrian provinces since more or less the beginning of the game, the governor had 9 points of influence and the cultural level was still on 50% level. To reach metropolis status you need 69%. If thats not possible to gain a single one percent after 130 turns by best possible circumstances, how should you manage to get 19% even during the long campaign? That's clearly not a challenge but a simple bug.
As for the first possibilty. I think the next metropolis should be Seleukeia or probably even Antiocheia. Therefore to build typical baktrian units you need to conquer nearly the whole Arche. Which is whether historical not a good gameplay solution.
No matter what, the Baktrian campaign is bugged on the current status. You simply cannot became a metropolis, regardless of your actions and further circumstances. Therefore whether the whole culture spread mechanics need to be changed or (a much simpler solution) Baktra became a metropolis. From the beginning on or via an event.