In the history of the real world, the medieval era ended with the fall of the Byzantine Empire and the goods of the silk road stopping short at the muslim world or ending up in venetian coffers. This prompted the first explorers, conquistadors and colonists to look west over the vast atlantic ocean for new trade routes to India, and instead they found the New World... Then found trade routes to India.
In this history there is already knowledge of the New World because the Aztec Empire tried colonizing Europe with 200,000 men, they were thrown back into the ocean by the Serbian Empire. They knew it was out there, but they did not have too much of a reason to go Westwards where there were clearly powerful Empires already ruling on the promise of riches they already had as the silk road was enshrined in the Serbian and Roman Empire.
For seven hundred years the Miroslav family ruled over the world from Iceland to India and everything in between, even the Mongol hordes could not resist becoming Miroslav. Everyone prospered under peace, because all of the Kaisers, Emperors and Empresses listened to the Serbian Emperor, the Patriarch of the Miroslav family. And if they didn't then the ol' Serb sitting in Jerusalem could pull the plug on holy gold or join the defending Miroslav to keep the status quo with a healthy dose of Gusars and mercenaries.
And then Emperor Vojislav II of Rome closed off the Mediterranean and Black Sea to Czar Vojislav of Serbia, who responded by closing off the Indian Ocean, North African and Alexandrian trade routes. Emperor Edward III of Britain shut off the North Sea to Emperor Luka of Scandinavia, who shut down the Baltics to Emperor Edward III of Britain and Emperor Rudolf III of the Holy Roman Empire. This prompted Emperor Medeni of France to close down the Frisian coast to Emperor Edward III of Britain, and this continued until everyone was imposing tariffs and trade restrictions upon everyone else. The world had quickly split between two blocs of alliances, alliances in both trade and military. The British Empire, the Holy Roman Empire and the Serbian Empire struck common cause against the Scandinavian Empire, Roman Empire and French Empire. The Ilkhanate and the Spanish Empire remained neutrally paranoid with both allied blocs, with the French taking a Spanish county north of the Pyrenees and the Iberians blockading Serbian merchants in Seville; and to top it all off the Ilkhanate and Spanish both distrusted each other as well, as Emperor Vuk maintained that he was the rightful Emperor of Spain whilst Empress Branimira of the Ilkhanate maintains that she was the rightful Emperor of Spain - this dispute going all the way back to when the Fraticelli Ilkhanate inherited Andalusia whilst the Catholic Hispanian Miroslavs tried to hold onto their old faith against the onslaught of the new religious order. When the Hispanian Miroslavs finally accepted the Fratielli sect over the Catholic one, the Iberian peninsula had been split permanently between the historical Emperors of Hispanian Miroslavs and the de facto Miroslav Emperors of the Ilkhanate who had conquered/inherited the majority of Iberia.
Anyways, they embargoed the Serbian Empire and were outside of either alliance, so Czar Vojislav decided it would be time to test the European waters and flex the Patriarch's military muscle to prove once more that the Miroslavs of Belgrad, Jerusalem and Alexandria were still the undisputed rulers of the Miroslav dynasty. Army group Tunis and Marrakech landed at Cadiz, after the Spanish and Ilkhanate navies were swept from the seas and cornered in their ports by Serbian blockades. Each army group had by standard 8,000 infantry and 4,000 Gusars each, making the armies well-rounded fighting forces. Cadiz was taken, and for a while it seemed as if there was to be no resistance from the Miroslav Mongols. Then 44,000 Mongolian soldiers and Mercenaries threw the Tunisian and Marrakechen army groups into the sea, killing 18,000 of the 24,000 who had set foot on Cadiz. The captured redoubt was recaptured by the Ilkhanate, whose forces spread out to meet any future Serbian assaults.
Czar Vojislav mobilized all of the army groups in North Africa, raising two more in Tunis and Marrakech, reinforcing the survivors of the battle of Cadiz and also mobilized the Alexandrian Expeditionary (which was above-standard strength, at 13,000 infantry and 5,000 Gusars strong) and even bringing another army group north that was previously moving to reinforce the Malian garrison. In total the Serbian army mobilized to attack Iberia was around 80,000 strong, with a supporting fleet of 151 ships. The British brought their own fleet to the fore as well, and in total brought around 30,000 soldiers to the Ilkhanate.
Diversionary attacks kept the Ilkhanate's forces guessing, so they spread out their troops. 12,000 Serbs landed in Gibraltar, drawing 15,000 Ilkhanate soldiers south. 26,000 landed just west of Leon, alongside 13,000 Brits - the bulk of the Ilkhanate's forces moved to kill the landing parties with the speed you'd expect of a Mongol horde, even one that had assimilated into the Iranian/Iberian cultures.
At the battle of Leon the 13,000 Brits and 22,000 supporting Serbs were defeated by the Ilkhanate's 40,000, routing them thoroughly. The battle however was very close, and the Ilkhanate's forces were thoroughly demoralized and ill-equipped for another battle. As it happens, 20,000 Serbians were just two days away from Leon, and in the second battle of Leon the Ilkhanate was thoroughly defeated. The Ilkhanate would attempt several counterattacks, attacking Edward III's smaller British detachments, always trying to destroy them before superior Serbian numbers could arrive and turn the battle. The Serbian detachments never strayed too far from Edward III's armies for this reason, making sure they were always victorious. Eventually the Ilkhanate was forced to surrender and reopen Seville, Emperor Vojislav wanted to cause as little damage to a fellow Miroslav as possible. He sent his armies east into Spain, where Emperor Vuk surrendered without a fight or siege - convinced that the 50,000 Serbian soldiers and fleets blockading the entirety of his country was reason enough to just reopen his ports for trade. Spain emerged completely unscathed, with only its pride slightly pricked.
Despite being victorious, Emperor Vojislav came upon the stunning realization that the Empires were now fully autocephalous, mature states led by unbowed Miroslavs in charge of armies who could rival the Miroslavs of the Primordial dynastic line. Realizing just how much of a perilous position the Empire was in, that the Ilkhanate could pose such a stubborn foe to the greatest Empire to have existed since the Alexandrian Empire; 70,000 soldiers were raised on the West Indian border with the Roman Empire, more troops raised in Jerusalem to raise the Arabian garrison to 40,000 - and if we're including the 24,000 in southern Arabia and the 22,000 in Alexandria, that number is raised to 86,000. The rest of the Serbian army (an additional 80,000 so troops) was stationed throughout the Empire to protect against revolts/pirates/Europeans and the unknown powers beyond the mountains and deserts that had historically kept the Empire isolated from the people of Cathay or the Nepalese on the Tibetan plateau (amusingly the Nepalese kept a permanent envoy in Jerusalem to maintain good relations with Serbia - it worked, both in the sense of appeasing the Empire and Vojislav's expansionist tendencies). These forces were mighty, especially when the Imperial Navy's 40 ships in the Indian Ocean or the 200 in the Mediterranean are factored in, boasting galleys, light ships, heavy carracks and cogs.
All the same, the rival triple-alliance also boasted 450,000 soldiers, and the Roman Empire herself was also a mighty naval power, one slip up from the British-Serbian alliance and Rome would rule the seas. The Holy Roman Empire boasted 115,000 men but was surrounded on three fronts, Britain had over 30,000 soldiers and not much more. For the Serbian Empire it was expand or die; if Emperor Vojislav could attain global hegemony he could force the triple-alliance into maintaining peace and preserving the health of the Miroslav Dynasty. War precedes instability, instability precedes rebellion - rebellion which could topple the rule of the Miroslav family.
So it is with a certain level of strange feeling that the Serbian Empire, the power that once ruled over all of the world from Iceland to India, stepped away from Europe. The Czar Miroslav was no longer King of all, and the Empire began to resemble more the non-extant Muslim, Greek or Persian Empires of old than the ocean spanning Empire Miroslav. Its capital was Jerusalem, its fundamental principle was religious unity and its religion preached asceticism, conservatism, the struggle against the evil and ignorance of the world - it pursued religious unity with the same fervour that was exacted upon the Zoroastrians of the Sassanid Empire by the Caliphates or the Ilkhanate.
Things were going well for as long as the Empires remained strong. Of all the dangerous borders throughout Europe two in particular were of especial worry to Emperor Vojislav; The French wished to take Genoa from Serbia, the Romans wished to take Rome from Serbia. He had a feeling the fate of those two counties could become very important in the future.
Then another thought struck him. Whatever did happen to the Empires of the New World? Within the Serbian court were court Aztecs, descendents from the survivors of the attempted colonization of the Serbians by the Aztecs, kept alive to keep their culture alive, their language known and all for possible future interactions. The result was a particularly strange line of Serbians who ran around in feathers and face paint, but they were interesting nonetheless. That was a long time ago... There had been no new words from the Aztec foe, no new attempts at colonizing Europe - no doubt the slaughter of 200,000 soldiers in the span of weeks suggested to the Sun-Emperor that Europe was a land of demonic warrior Serbs who lived to remove Aztecs from the premises. The last word that had been heard from them was that the horrible diseases that had infested Europe had been transported to the New World by the folly of the Aztecs, and that they had captured some good European horses to use in war against some other distant Empire simply known as the Incans, who were said to wield sticks that fired thunder.
Vojislav could not shake the feeling that whilst he looked to carve out his Empire of one land and one continent, somewhere across the seas there was an Empire of people with far more warriors than sense that might have an interest in taking advantage of a polarized and disunified Miroslav family. Then again, the Incans and Aztecs had disunity of their own. Whilst he did have little interest in taking over lands he could not march his armies over, he was always in the business of removing threats to Miroslavs...
tl;dr, 45th try was successful. The Empire has gotten considerably more religious, and has expanded far enough to West Africa that it has reached the coastline. The wars between the great powers of Europe have been limited both in scope and geography, happening only in the Iberian peninsula with relatively little bloodshed. Still can't decide on whether to get expansion or exploration as an NI. I'm leaning towards exploration just because that +25% naval force limit makes it of far more use in the long run than more trade power or quicker ship construction. And now to download a new After the End for Miroslav 2 apocalypse boogaloo.