What PoDs Would Create An Unrecognizable World?

One idea is that there isn't an ice age or that the dominant species of human isn't homo sapiens. Another idea could be that Rome never becomes a superpower. You could have the Greeks never unity and thus everything we know about the western world never happens.

Some ideas not really looked at that I think could be interesting given enough time :

To Rule, Be Greek : Basically, one of the major problems that the Seleucids and Ptolemies faced when attempting to Greekify their domains was they gave no incentives for the native population to actually go to Greek and stay Greek after being conquered. In Bactria, iirc, the requirements to be a member of the ruling/upper classes was basically you had to convert to the Greek Pantheon or just learn to speak and write Greek and dress in Greek Attire, which greatly incentivized Hellenization of the native populace there as it basically meant you could be a member of the ruling class by just changing your religion and language to fit with the rulers of the land. Both Diadochi states tried to get as much Greek colonization from Hellas, but there was no incentive for the greeks to go there (Since Macedonia was likely going to always keep the Barbarians away, which would be any major reason for a Greek diaspora) pre-rome and by the time of Rome's conquests, either A) The state had effectively abandoned trying to gain greek colonization and slowly began to be converted into the local culture (Ptolemies) B) were fighting a Civil War/Native Revolt every decade, making the realm to unstable and really not that enticing to go towards for a new life, and C) Rome wasn't harsh to the Greeks, so they had no reason to flee. Any forced attempt Latinization of the Greeks would've seen some large scale revolt and if crushed, might've led to a diaspora, but by then, where are they going to go? By Rome's conquests, the Diadochi States are falling apart, Carthage is a non-factor, the Greek colonies in the West are protected by Rome and under it's influence, including the critical city of Syracuse, there's untamed barbarians that'd likely kill them if they went north, and the minor states in Asia minor will be swallowed up by Rome eventually.

Setting a POD to Antiochus I Soter's reign where he makes the decision that all you need to be a ruling member/part of the elite is to be greek might see Syria, Asia Minor, Mesopatamia, and maybe a decent portion of Persia to Hellenize. Give that a century, maybe two, to simmer and you might have a pretty large greek population in the two Diadochi states outside of Greece, which might have pretty big butterflies if Antiochus II Theos successfully repels the Parni so the Parthians don't get a major foothold in Persia, allowing for Persia to be relatively stable and loyal for a time. The farther east you go, the less hellenized you will be. But still, imagine when fighting, Rome faces a more unified Diadochi state that doesn't have the internal strife and Native uprisings per OTL. Furthermore, they could potentially colonize Arabia, leading to Greco-Syrian, Greco-Persian, and Greco-Arabian Kingdoms when the Seleucid Empire inevitably ends, creating massive butterflies. This is an interesting concept to think about. This would definitely to a more helenized east and maybe a greater distaste for the Greeks in the West, which would be unthinkable

Alexander the Conqueror : Alexander I of Epirus, Uncle and Brother-in-law of AtG and Uncle of Pyrrhus of Epirus, isn't killed in the Battle of Pandosia and wins, going on to conquer much of the Peninsula, and conquering Rome, creating a mini-Empire in Italy for Epirus. This leads to a Greek effort to colonize the Italian interior in some fashion and depending on what happens, the showdown between superpowers could be Epirus against Carthage and in that fight, I have no idea who wins. Main effects will definitely be no Rome, but also greater Greek Influence in Italy, maybe Gaul too depending on Massalia. Would definitely lead to an interesting world without Rome.

Phalanx on the Elbe : A greek colony is founded either on the coast of Germania or in Germania's interior along the Elbe River The tribe in the region adopts some greek ideas while the greeks adopt some German customs, creating a unique Greco-German culture not really seen elsewhere in Europe or the world. Slowly, this tribe's influence expands and is able to form some kind of federation/Kingdom in say Hanover. This Kingdom is Germanic in some aspects, but Greek in others and that scares Rome, who tries to get it dismantled, only for these plans to be stomped out. Eventually, this Kingdom goes with the Migration and depending on what happens, maybe its successor in the old Western Empire could be slightly more advanced than its neighboring counterparts. Any ideas for what may come next?

These are just a few. If you want to do anything with them, feel free to.

Just wondering as to what kind of PoDs would result in the creation of divergent dialects of Greek that will become separate languages in their own right, much like how Vulgar Latin had offshoots that became Spanish, Portuguese, Italian, and French, as well as other Romance language.

True, although if Caesar had survived the failed invasion of Britain, he could be a bit more cautious in his political career. Maybe he might not do something stupid that led to his assassination at the hands of the Senate.

OTL Volga Bulgaria was founded in the 7th century, well before the rise of the Rus'. In this scenario, a Kievan or Dnieper Bulgarian state would have been a major barrier to any potential horde invading Europe. Since Khan Kotrag and his tribe would be ruling over a large population of East Slavs, they may eventually assimilate into the local population, much like their cousins in the Danube. The Khazars in this case would bear the brunt of the attacks from other tribes in the Pontic Steppe, like the Magyars and Cumans.
True, although converting to Christianity might depend on who gets to convert him, that is the main question. It would be easy for Sartaq to be baptized by a Russian Orthodox priest, making a Christian Golden Horde more appealing to their Rus' vassals. 

Another thing too, was that Bulgaria also had a Genghisid ruler as well. I also wrote a TL on this very premise as well, but it involved Sartaq converting to Orthodox Christianity, not through their Rus' vassals, the Byzantines, or even the Bulgarians, but rather the emerging Kingdom of Serbia under the Nemanjic dynasty.

en.wikipedia.org/wiki/Chaka_of_Bulgaria

Here you go:

1. Westrogothia and Ostrogothia: The Goths settle in the Iberian peninsula and successfully eliminate the Romance language there, replacing it with their own, while the Suebians had settled along the central and upper western coast, creating their own kingdom there that was in dynastic union with Westrogothia for . To the east, the Balaeric Islands hold the small Vandal tribes who create their own strong government till the Arabic invasions, when they return to Europe and head west, then set sail, not to be heard from again till the 15th century, when the Suebians discovered the Lost Vandals on Madeira, the Canary Islands, and the Azores, with three distinct languages with multiple dialects. The Gepids occupied the southeastern part of Europe, while the Ostrogoths were pushed out of Italy by the 700s, and they settled in the basin we would know as Transylvania and north thereof, preventing the magyars from settling within western Europe. Southern Slavs never reached the west and settled in what we would call Romania and Bulgaria, while the Burgundians settling in southern France became romanized, a 500-year-sister tribe of Burgundians had settled in Crimea, being off the radar for most of history until their kingdom re-emerged on the scene around the end of the first millenium. East Burgundy, as it was called, was subsumed by the Khanate, then the Golden Horde, placed under Lithuanian protection in 1389, and achieved independence in 1612. The Romanians as we would call them settled west, as their place was displaced by the south slavs, placing this timeline's Romania in the territory of what we would call 'Yugoslavia', subsuming the Albanians into their nation until the Albanian language went extinct in the 19th century, becoming a historic curiosity to linguists. The Seventh Crusade, or what historians would call it, resulted in the recovery of Constantinople in 1514, and resettling many Greeks there, but the Ottomans proceeded deep into Europe for much of the 17th and 18th century until they were pushed away from Vienna and central Europe and finally out of Constantinople by 1877 with a combined forced of Romanians, Austrians, Burgundians, and Ostrogothians, the Bulgarians and other South slavs on the Baltic coast providing what little help they could to the effort. Being so occupied, these various nations never participated in colonization as much as the British, French, or Germans did. In the New World, a lost tribe of Norse had managed to settle and hold onto Newfoundland, St John Island, and Cape Breton Island, with evidence of their having traded far south, their foreign diseases and alcohol having wiped out a number of native tribes unknowingly, making future colonization by Europe much easier.

Here are a few ideas I have. I'm sure any one of those could do the job nicely.

1-What if the dark ages never happened and the scientific, medical, and engineering advances are simply never lost. We would be about a thousand years ahead of where we are today. We would live in a world of starships and FTL speeds. A world that has us mining the asteroid belt and colonizing other solar systems.

2-The United States fails to gain its independence from Great Britain and we remain as a part of the empire. The empire of course doesn't fall apart post world war 2.

3-The USSR lands on the Moon first and the space race doesn't end. The first man on Mars happens sometime in the 1990-2000s.

4-The personal computer never takes off. Computers remain something found only in offices.

5-The Able Archer exercise sparks World War 3 and we now live in a post-nuclear attack.