Two Different Versions of Alexander's Empire Surviving
One of the great hinges on which history turned is the death of the Macedonian conqueror Alexander the Great. Using the combined war machine of Macedonia and the classical Greek city-states, he conquered the gigantic Achaemenid Persian Empire and even some regions outside it in a very short time. He ruled from northern Greece to Egypt to outer India and Central Asia, but before he could consolidate his government and create a lasting dynasty ruling over most of the known (to Europeans) world...he died of a fever, excessive drinking, or a combination thereof. And his generals tore the empire apart, sidelining and killing his wife and son in the process. Had Alexander lived, it would have been a very, very different world, and people have been wondering about what might have happened for a very, very long time.
(One of the earliest works of alternate history is the Roman writer Livy, who wrote a short scenario in which a surviving Alexander fought Rome. He thinks the Romans would have still won, which is...dubious.)
And the alternate history forum which I still check in on even though I'm self-banned (which keeps me out of the cesspool that's Political Chat) has two different versions of one surviving-Alexander timeline, "Blood and Gold." Here's the first version and here's the second.
*Apparently before his death, Alexander was planning a campaign to subjugate Arabia, which was the crossroads of a rich spice trade. Given how he lives longer this time around, we see that campaign.
*Alexander's Macedonian supporters were growing increasingly resentful of his adoption of Persian customs in order to govern his enlarged empire. This continues to be an issue for Alexander himself and his successors, who govern from the Middle East rather than Greece. And since the Argead (Alexander's family) often practices polygamy, this leads to all sorts of harem intrigue and problems.
*India continues to be a thorny issue for Alexander and his successors, as by the time Alexander heads back for round two (his army mutinied rather than try to advance further the first time), Chandragupta Maurya has founded his empire. Maurya is Alexander's equal and western India is going to be contested zone for generations.
*Alexander soon finds himself embroiled in the politics of Rome and Carthage, the two great powers of the Mediterranean. This is is also going to be an ongoing issue.
Both the original version of the timeline and the revised timeline are dead now and there's apparently a third that's also dead, but they're long and they're fun reads while they last. Enjoy!