In the Balkans, well, it was a tumoltous time. After the Plague crippled the Hungarian state which was in loose hegemony over the region, the Bulgars begun to grow even more restless then before. The Hungarian vassals of the Asen dynasty were dying out anyway, but their demise was sped up by the 1437 by the impatient peasants. They found themselves TWO charismatic leaders - a nobleman, Matvey Matuski, and a Non-Reunionist (i.e. rejecting the reunion of the Western and Eastern Churches) Orthodox priest, Grigori Bashan, better known as Father Ioann. The new Catholic clergy, largely consisting of "defected" Orthodox priests, was not liked much in Bulgaria, where most of the population bitterly rejected the Reunion. The peasant rebellion resulted in a massacre of the said clergy and in the expulsion of Latinized parts of the nobility. Citizens joined the rebellion - Matvey and Father Ioann were a very charismatic duet, and soon enough they managed to organize a strong, if badly-organized and untrained army. With fanaticism, the Bulgar peasants and citizens armed themselves with swords, axes, bows and arrows and when they ran out of all that with blacksmith hammers, chains (this proved frighteningly effective) and cooking utensils, as well as agricultural tools. Also, guligrads, rolling wooden wagons, were adopted, mostly for the defensive action in plains of Eastern Bulgaria. Hungarian crusaders were routed at Nish, Constantinople was besieged and Matuski secretly acquired Ayyubid support in the form of a few brand new cannons - Sultan Al-Wahil was only too happy to arm some infidels when they wanted to kill some other infidels. Good business, beside that. Constantinople soon faced an Orthodox rebellion within and artillery bombardment from outside, and soon enough the ragtag Bulgarian army entered the city. A Venetian-Hungarian-volunteer crusader army was badly beaten at Trnovo, again underestimating the bravery of the Bulgarian rebels, but eventually managed to win the Battle at Salonika against the advancing army of Matuski. The would-be Tsar of Bulgaria died, and all seemed bleak for the rebels, if not for Father Ioann, who by then triumphantly was declared the Patriarch of Constantinople and declared the end of the Reunion, causing instability in Russia to culminate in the Russian War of Religion in 1458. Assuming command over the Bulgarian rebels, Father Ioann personally led them to victory, promising absolution of all sins for participating in the holy war against the "latinists" (OOC: note, warrior-monks, or rather general-monks were not uncommon in Medieval Europe. Notable OTL example a Catholic bishop named Konrad Piast, who personally crusaded against the Hussites). At Trnovo, the crusader armies were routed - heavily armored knights were captured en masse due to their cumbersome armor, and pleaded for their lives, but Ioann took no prisoners. Well, he did take prisoners to interrogate them and to only grant them freedom if they pay out a ransom AND convert to the Orthodox Church. To the honor of most knights, they refused, albeit a certian percentage of them did. At this point, in 1444, the crusades begun to run out of steam - not even the promise of complete, unlimited plundering opportunities lured many volunteers now, as Bulgaria became a byname for death. Father Ioann, surviving several Inquisition-organized asssassination attempts, besieged and took Belgrade; much of the Balkans outside of Greece were now his, all his. To formalize this, he had himself crowned the True Holy Roman Emperor in Constantinople. Bulgaria was now renamed the True Holy Roman Empire, albeit to avoid confusion most historians called it the Holy Byzantine Empire.
Holy Byzantine forces continued to win, eventually taking control of Venetian mainland Greece and of Hungarian Wallachia and South Slav provinces. Emperor Grigori-Ioann I the Holy (or Unholy according to the Catholics), founder of the Bashan Dynasty (which had firm hold in one person on both the Emperor's throne and the Patriarchate, merging the two offices effectively), died happy in 1464, the founder of a great empire. Which was only beginning to expand (OOC: an Orthodox Patriarch becoming an emperor is not all that unlikely. In much more normal circumstances this almost happened in OTL Russia in 15th century).
The consequences of the Bulgarian Crusades and the failure thereof were manifold. The Venetians and the Hungarians were weakened further - Venice lost its Crimean possessions to rampaging Tataro-Cumans, being cut off from them, whilst Hungary was thrown into a many-sided civil war between Angevin, Wittelsbach, Piast and Rurikovich pretenders - this war will be an on-and-off one, and during its the Hungarians will also lose Moldavia to the Holy Byzantines. Hungary was partitioned and reunited, and Italian, Bavaria, Polish and eventually Russian armies intervenned en masse. Mercenaries of the Catalun Company conquered Croatia for a while, but eventually were stamped out by the Angevins, who by the end of the century were beginning to gain an upper hand.
But the worst came in Russia. There, Non-Reunionist Orthodox priests persisted, especially in the northeast. In the grand city of Vladimir, using the youth of King Igor II, the pretender Gavriil, supported by the Non-Reunionists, used the growing instability to rise up, starting the Russian War of Religion in 1458 - this was the event that allowed Valdemar of Denmark to start his Hanseatic gambit. At the same time, Tataro-Cuman tribes smelled blood and besieged Kiev; they were only barely defeated. The Orthodox and Catholic armies clashed in the fields of Rus, and neither side could attain victory. Taxes grew sky-high to ensure funds for continued war. Peasants rebelled, opportunistic warlords appeared. Monasteries, already often fortified, now were often besieged and became genuine impregnable fortresses (OOC: in OTL, pretty much the same happened in the Time of Troubles. Monks with swords and crossbows often held off huge regular and irregular armies and even defeated them). Cities were being looted by both sides at the first opportunity. Cumans raided the periphereal lands.
But the Pope was determined not to lose Russia too. He called for a crusade to help the now-mature Igor II. He found some restless German and French knights, tired of the peace. Well, it was a start... As crusaders poured in, Gavriil, much less capable a leader then Father Ioann, faced defeat and finally was crushed at Ryazan in 1471. What followed was the revenge of the victorious Catholics. Non-Reunionists were massacred, their monasteries burned, their women raped, their cities (hard as it was to find entirely-Non-Reunionist cities...) were looted. The Russian Inquisition soon gained the reputation of the worst in Europe. Led by Father Aleksander, the Inquisition started a brutal witchhunt - or rather, Non-Reunionist-hunt. Anybody suspect of Non-Reunionism faced violent death. And meanwhile, peasants, warlords and Cumans were still being put down. Russia was set back in its development by a few decades by this.
And finally... As religious tensions threatened the integrity of the remnants of the Catholic church, Pope Adrian VI, of French descent, was quite inclined to compromise with the rising (thanks to the printing press) Reformist movements. Catholic Church was effectively reformed, with the worst excesses of inquisition and indulgence-sales curtailed. Some die-hard Catholic priests protested, but most didn't mind too much.
The Marinids were flourishing in this time. Abu Masuf (r. 1424-1475) was one of the greatest Marinid rulers ever - not only did he greatly modernize the fleet and employ the experienced Barbary Pirate sailors in it, allowing him to defeat a Spanish invasion attempt, but he also solidified his rule over Northern Africa and expanded his empire far to the south, across the Sahara to the prosperous West African trade states. Um, technically far from all of these conquests were actually useful. But some of them were, such as both banks of the central Niger River. The Marinid Sultanate ruled supreme in West Africa, basically, also expanding into Tripolitania in the east.
The Ayyubids, eager to keep up with their western neighbours (as they - the Ayyubids - expanded into Cyreneica), too reformed their navy, modernized it and thusly beat back the encroaching Venetians. These reforms were backed by money, lots of it - the Ayyubids were helped by their trade with the Chinese, whose merchants now occasionally came to the Red Sea... but every time they came, it was good trade! The Ayyubids also adopted some of Chinese ideas, about ships. The new, armored, huge cannon ships especially. They later would become very popular in all of the Mediterranean, and a variation thereof would be used by Ciano Polo in his western expidition. Thus it was that slightly-modified junks would become the basis of European naval technology in the Age of Discovery.
The Swahili Muslim city-states of East Africa united under the authority of the Sultan of Mombasa. The Mombasians also eventually expanded all over the Horn of Africa, only to be stopped at Adal by the ancient Ethiopian kingdom.
In the Middle East, there was much turmoil, but no decisive results at first - the Ayyubids, the Kemalids and the Rumians were perfectly capable of holding their own territory, and perfectly uncapable of capturing anything else. Things changed slightly in 1437 - the Rumians, the weakest of the three, collapsed into four states - three Turkish sultanates and one Greek kingdom in Trebzond. The westernmost Sultanate, of Smyrna, was in 1471 conquered by the Holy Byzantines; five years earlier the easternmost Sultanate - of Dulgadir - was captured by Ayyubid armies. Keraman and Trebzond survived... for now.
Kemalids were perhaps in their apogee. Al-Hasa and Oman were subdued, control of much of western Central Asia was unchallenged, Georgia was beaten out of Dagestan (including Aizerbadjan) and firm control over northwestern India was established as far as Ganges and Narmada. In Deccan, however, the Hindu-Muslim empire of Bahmanistan expanded to the very tip of Deccan in the south and Mahanadi in the northeast. Bahmanistan was a very strong state, forming a bulwark against Kemalid expansionism - though the Kemalids weren't exactly eager to conquer more rebellious Hindus and whonot. Shahdom of Ilyash was a rising power in the Gangetic Plains, albeit it still had much competition from Nepala and Bengali and Jharkhandi states. Sinhala continued to prosper as a trade hub.
As Mongolia expanded west and the Kemalids expanded east, a power vacuum still remained between them in Central Asia, to be later filled by the rising power of the Kyrghizian Khanate. The Khanate threatened its western and eastern neighbours alike, and succesfully raided the lands of both while they were distracted elsewhere, whilst most punitive expeditions were crushed long before the enemy came close to the Kyrghiz capital - Kucha.
Indian and Pacific Oceans were during this century filled with Chinese trade. The flowering of Chun trade touched cities from Mombasa and Aqaba (the latter growing into a great city from a pathetic fisher town almost overnight) through Muscat, Soccotra, Rayigama and Singapura to the rising Mu'lan-Pian ports - Hasen (OTL Seattle), Fusong (OTL Los Angeles), Soconusco and Chan Chan.
Mongolia became increasingly urbanized during this time, especially as its center of power firmly switched to the Sinified south.
Mongol-Chun border wars got even more frequent during this century. The Mongols were handled a several defeat at Linfen in 1411, but in 1443 got something of a revenge by annihilating three Chinese armies in three separate battles within Mongolia. Basically, neither China nor Mongolia could subdue each other. These wars were actually very expensive, especially for China, but luckily it was fuelled by the great maritime trade. Also, the Chinese after 1443 abandoned their attempts to conquer Mongolia, and instead greatly modernized and extended the Great Wall, concentrating on expansion in other directions - most notably, in Mu'lan-Pi, but also in Indochina where a combined overland and maritime invasion finally subdued Annam in 1445-1454, albeit rebellions there were frequent until the enraged Chun resorted to wholesale genocide and resettlement programs in 1480s. This actually had a good effect - albeit these areas remained unstable, the Chinese not only got lots of people to use as colonists in the barrens of northern Mexico and points north, especially northwest (jokingly the new province was renamed Sinannam, New Annam - which brings up another point: if Insane Panda is born in this world, it is most probable that he still would live in South California, or nearby anyway), but also turned the Annamese into a rather small minority in their own country, now trully worthy of its name (Annam being Chinese for "Pacified South"). Chinese rule was also extended to the Luzon and Mindanao, and the small nearby islands as well.
In the rest of Indochina, Shwedmawazedi, a visionary Burman leader, led Pagan to a sort of cultural and political renaissance, unifying much of Lower Burma during his lengthy (1435-1489) reign. His heirs weren't quite as good, but Pagan still did expand northwards during their rule. Eastward expansion was blocked by the great power of Siam, which now controlled all lands between Annam and Pagan. Melayu didn't do well - Sumatra was lost to the rising Sultanate of Atjeh, which conquered roughly a half of the island, whilst the rest was overran by the expanding Siamese, who grew fat and wealthy from trade with China and India.
The other half of Sumatra was controlled by the rising Hindu-Buddhist ("Shiva-Buddha Cult" being something of a dominant religion) empire of Singhasari, which ruled all of Java, southern Borneo and western Celebes, as well as lots of puny islands here and there. A great naval power, the Singhasarese nonetheless got along well with Chun China, assisting them in the wars against tiny Malay statelets that tried to unleash privateers on Chinese shipping. Said statelets were eventually conquered by the Singhasarese Atjehian and Siamese allies.
Western Mu'lan-Pi was the site of a grand colonial game during this time. Japan consolidated its hold on Shinihon (OTL North California, Oregon Territory and much of British Columbia), whilst the Mongols established some colonies of their own in Yupeka (OTL Alaska, Yukon and northernmost British Columbia). China remained the dominant colonial power, ofcourse, now in control of all of Mesoamerica save for Mayan and defiant (and since 1439 unified under Mayapun) Yucatan.
The Chinese "gold junks" were frequently raided by Japanese pirates who took to the ocean. To make this even more of a ripoff, the most fearsome Japanese pirate was called Frankiga Drakonami. Meanwhile, a Japanese faction came to power in Hawaii, but the Chinese faction was occasionally trying to overthrow it. Poor islands...
China fought and won a war with the Incans in 1462-1471, annexing many of the Incan Empire's northern lands. Incans swore revenge and started numerous military and administrative reforms. A Chinese protectorate was established over the excessively rich Chibcha lands. China was a great colonial power already, but soon enough more upstarts came. Dirty, babbling, round-eyed Far Eastern Barbarians (called so for being even more eastern then the Eastern Barbarians - Aztecs and their relatives). Their captain, Ciano Polo, whose expedition reached "Mulanpy" in 1441, was extremelly excited. China! But everybody knows China is in the EAST! So this means that Earth is round! Roundy roundy roundy round! Either that or those Cathayans are very tricky bastards. He wasn't one bit disappointed to learn that this is Mulanpy - everybody knows that Mulanpy is in the east, to the east from China itself, so it is only logical that on a round Earth Mulanpy would be to the west from Spain! For all of his flaws, Ciano Polo was a smart man, madman that is. And a crafty merchant as far as simpleminded Far Easterners went. Trade links between Europe and China thus developped via Mulanpy. Spanish trade posts were set up for that purpose in the Carribean islands, most notably Hispaniola and Cuba, and lesser colonies were established in Florida and Venezuela, all of which have the exact same names as in OTL due to an odd amount of coincidences. Some silly adventurists tried to conquer Yucatan, but the Mayans beat them up with humiliating ease, though some claim that there were Chinese officers commanding them. We'll never know the truth...
England and France also arrived in late 15th century, but had to contend with fishing outposts in Newfoundland and Acadia respectively. The Mulanpan natives weren't as good trading partners as the Chinese, but they did have nice furs. Um, that is they were good fur traders. Not excesivelly furry themselves though. Meanwhile, Delaware and Huron tribes rose in power to wrest the control of the fur trade from their lesser neighbours and to make sure Europeans don't get very uppity if they ever come to their respective lands.