Not a timeline, but an idea. I feel both would be interesting ideas to map. You could choose the rome doesn't exist and make either a Strong Macedon or Carthage. The whole purpose is to decide how you would represent the idea
For the first you could go Agent of Ctesiphon where The Persians dominate but either Roman fragments survive or you have the Romans and Greeks revert back to either The Pantheon or something else. The second pretty much Years of Milk and Honey So Europe basically partitions the world.
Alternate history challenge create a map that is the reverse of Agent of Byzantium Or something like a reverse years of rice and salt. Where other powers dominate the world. Pod is the black plague where it strikes should shape your world.
What if we end up with a situation similar to Agent of Byzantium, but perhaps the western Roman Empire survives and the eastern is affected by the goth invasions changing the religion that the fragments of the eastern support.
I will elaborate those which were rejected by the council of Nicaea. So would it be possible for these gnostic religions to somehow survive till the present.
Is it possible to have another form of Christianity exist today, examples Valentian, Cathar, Bogomil or others .Or are they likely to be absorbed by The dominant Catholism or Orthodoxy.
Create A title for alternate history novel which doesn't exist.
Years of Oil and Wheat-A world where the black plague wipes out The Asian world along with India and Africa. This is the story of the great powers Rhomania, Francia, The Isle of Anglia and other European powers left to recolonise...
Whether you decide it to be one world or multiple separate. This is up to you. My two cents. Al Andalus gets backup from other islamic powers causing the Iberia to never be Christian or the Moors become an earlier version of the Ottomans in other words the Boogeyman of Africa. Rhomania or...
Rebellion - The story of a British Duke who leads a rebellion against the Scottish Union of the Isle of Anglia while fighting a war with Oranje.
The Mouse that roared- The story of a Bolivian warlord Simon Bolivar who conquered most of Southern Atlantis.
Tyrian Skys- The Story of an Alternate...
Create an alternate history tv series that does not exist .
Rebellion - The story of a British Duke who leads a rebellion against the Scottish Union of the Isle of Anglia while fighting a war with Oranje.
The Mouse that roared- The story of a Bolivian warlord Simon Bolivar who conquered most...
To elaborate it's up to you write something that is believable and not going into ASB territory. For example the only way Rhomania has an empire of Justinian peak till at least th modern times would be to do extreme massacres as seen in the defunkt timeline Out of the Ashes.