2 ahistorical goals.
Arguably 3. Most historians estimate Cordoba and / or Kaifeng were larger than Constantinople around 1000AD.
But given the history of the Byzantine Empire in the timeline of this mod, the historical goals would be a bit rubbish:
UHV1: Lose all Asian territory by 1080AD
UHV2: Lose your capital by 1204AD
UHV3: Die by 1453AD
The general consensus is that the current historical goals are much too easy, so unless we are going to add a load of code to simulate the Byzantines' periodic crises and collapses, which would just make them a pain in the ass to play, then we need ahistorical goals if we are going to have any fun at all!