Manuel I Komnenos won the battle of Myriokephalon in 1176, regaining most of Asia Minor and starting a Byzantine resurgence. His son Alexius II managed to survive to the Andronikos's assassination attempt becoming one of the most great warriors of his time, succeded to defeat completely the Seljuk and then started to advance in Syria and the Holy Land. The Mongol tide halted the Byzantine "Reconquista", but soon Rhomaion was able to continue the march on the south and finally to conquer Egypt in the beginning of 13th century. Meanwhile the Komnenid diplomacy started to set more peaceful relations with both HRE and the Normans, throwing away all claims on Italy and accepting to not harm the last crusaders enclaves in the Holy Land. New favourable relationships were reached also with Genoa to counter-balance Venice (saw as more hostile towards the Empire), and with the Iberian christian nations, expecially Portugal.
Soon the Empire turned its eyes on Mediterranean Africa, but here the advance was more slow because of islamic revolts, Hungarians attacks to the North, Venetian and Berber pirate raids and the Timurid invasion but in late 14th century the conquest of Maghreb was done with the help of Portugal (where a Komnenos cadet line obtained the throne because of inheritance) and Genoa, who gave ships and valuable commanders to the Empire.
Meanwhile the terran routes to India and China were stopped because of hostile Muslim nations of the East: Golden Horde, Hedjaz, and the Timurid Empire later assorbed to Safawid Persia. So the Empire in 1492, instead to follow the African sea route like Portugal, he agreed to finance the expedition of Genoese admiral Christopher Colombus who claimed to reach Asian land across the Atlantic Ocean. Departing from Tangiers, the 12th October of that year Columbus discovered the island of Komnenia (AKA Hispaniola) and claimed it for Byzantine Empire. But soon Rhomaion wasn't interested so much to these new discoveries (also because it was more interested to the first Italian wars between France and Spain), Columbus falled in disgrace and the exploration of the area stopped; however the Empire started to colonize Komnenia, mainly with Greek and converted Turks but also with a small number of Genoans merchants.
The Byzantine expansion in the area restarted when it was clear Columbus discovered a new continent which Western Europe called America from Amerigo Vespucci who first recognized this statement (but the Empire reclaiming the discovery gave the name of Columbia to the New World). The so called "scramble for Columbia" started when the Spanish in 1511 conquered Cuba, while two years later the Byzantine started to build their first colonies in the island of Saint Sophia (AKA Jamaica): this possession was later lost to the English in 1660 but in that period it was vital for the further expansion to the West. Soon both Spain and Rhomaion looked to the continental masses, hearing of the "golden realms" in the region: the first expedition were Spanish, but the Byzantine managed to spread their influence in 1518, just few months before Cortez's expedition. The Spanish "conquistador" so decided to invade Yucatan and he went to South until he reached Panama. Returning to Byzantine, after founding the city of Isaacheia (AKA Veracruz) in 1519, they started to expand towards the Aztec Empire until its conquest it in 1521.
Soon was proclaimed the Vicerealm of New Hellas, known also as Mexico as the natives called their land from a interpretation of the former Atzec capital's name, Tenochtitlan, now rebaptized as Nova Costantinople. The region was soon forced to a massive orthodox conversion and a Greek and Turkish migration (but also small groups of islamic Egyptians and Maghrebians who formed a little but strong community in the region), while Rhomaion continued its expansion to North Columbia conquering in the next two centuries the now USA South-West states, the most important to Byzantine colonization were New Egypt (Texas) and Pacificheia (California); in that last country were founded the now two main Columbian cities on the Pacific Coast, Saint Eirene (San Francisco) and Angeloseia (Los Angeles)
Rhomaion maintained, despite the heavy pirate raids againist its gold and silver convoys, a stable control of the Vicerealm for almost 300 years, also thanks to the loyal submission of the natives, who were the clearly majority in the region but were regarded as second-class citizens.
The Orthodox Church guaranteed the general stability, also because of the crescent fame among Mexicans of the Marian sanctuary of Coatlaxopeuh (I used the atzec name of Guadelupe because i don't find a suitable name in greek) near Nova Costantinople. The Byzantine also managed to added to the Vicerealm the Yucatan peninsula after the war of Spanish Succession, while previously lost as said before Saint Sophia (called now Jamaica by the English) and West Komnenia to the French (now Haiti). But the losses in the Caribbeans were not important for the Byzantine, while they considered Mexico as their "jewel in the crown".
But after the Revolutionary and Napoleonic wars things were going to change, a large separatist revolt started in the Vicerealm since in 1809 and in 1813 Mexico proclaimed its indipendence. Rhomaion tried at least to create a puppet Empire, but failed and in 1821 it recognized the new state obtaining some privilegies focused on the rights over Coatlaxopeuh sanctuary and the right for the Emperor to maintain the tile of "ruler of New Hellas" despite the Mexicans gived to theirself a republican constitution ( but the "imperial" concept was always strong in the country, because many ambitious tried to proclaim an empire of his own in the first century of Mexico indipendence).
Today Mexico, despite it lost the territories north of New Nile river (AKA Rio Bravo) after the war of 1848-1849 with USA, is the main regional power in Central Columbia and the only Orthodox state in the entire continent (in Jamaica with the English domination most people converted to Anglicanism, while Komnenia is split into Catholics and Orthodoxs). His main economical partners are the USA, despite pressant issues as immigration and the lower consideration the middle Americans have of "Greciards" ( the discendents of mexicans in the now USA territories); but also the other Greek-like or Orthodox nations, expecially Rhomaion and Russia.
