To the south lies the Fatimid kingdom of Egypt. They are often aggressive against the Byzantines, but frequent Crusades for Jerusalem can easily distract them and make for an easy war.
Byzantine armies are mostly heavy infantry, as is the case for most Christian factions. In the case of AI versus AI, the Byzantines usually fight off the Seljuk invasion of Armenia, but usually lose the invasion that the Fatimid launch towards either Anatolia or Greece which is launched some time afterwards. From there, the empires fortunes will fluctuate, and a lot depends on the impact of the hordes on the Muslim world and the stability of the Seljuks. But they generally survive to the end game
In the DLC "Legacy of Rome" the Byzantine Empire receives a new type of invasion unique to them: Imperial Reconquest. Using this, the empire could reconquer all of the de jure territories of the late Roman Empire and recreate it in the middle ages. In order to do so, you first need to create the title "Roman Empire " as well as mend the "Great Schism",which will convert Catholicism to a Christian heresy, thus making the process of changing Catholic provinces to Orthodox much easier.
They have their own mercenary unit, The Varangian Guards(don't give them land), which can be used as a first strike unit during the start of a war, giving the player time to gather their levies into a proper army. While upkeep can be troublesome, having a high income county such as Constantinople can help offset the costs. Unlike when playing a Catholic country, the player can appoint their own head of the Orthodox church called a Patriarch, who can't call crusades.
Your capital, Constantinople, is your most important holding as at the beginning of the game it already has four city slots, two castles, and a temple. The Byzantine empire is essentially built around the city. Constantinople is also home to the Patriarch of Constantinople, head of the Orthodox church. Constantinople is a major trading hub between the Black Sea and the Aegean and Mediterranean. The city was originally founded by a petty Greek king named Byzos - hence, the name of the city, Byzantium, which was later applied to the realm of the Emperor that ruled from the city. It fell under Roman rule during their expansion into the East, later becoming the capital of the Eastern half of the Empire during the period of division between senior and junior Caesars. Constantine the Great, the namesake of the city, ruled over it as Emperor in the East. Constantine became the first Christian Roman Emperor. Rome, of course, did not last - several sacks of the city by Germanic tribes ended any remnant of Roman rule over the West. Byzantium, then, became the capital of the Roman empire in the East - and, in fact, the citizens of the city would call themselves "Roman" well into the Ottoman period.
Your secondary cities are Thessloniki on the European side and a trading hub , Nicaea on the aisan side and very close to Constanople and Adrianople on the European side very close to Constanople also which all hold 6 slots.
The Byzantine Empire in 867 in the Old Gods DLC. As oposed to earlier games This version is substantially easier, allowing to be both more agh to start at the old gods, or Legacy of Rome standpoints. It is truly easy as you will for any good player,but there will be challenges as in the other start date. In 867 the Byzatine Empire is one of the most powerful empires, it having one of (if not) the largest levy in the game, it is also the only Christian empire.
Your main enemy will probably be the Muslims to the South, in this start date, you will likely face the empire to the South, the Sunni Caliphate. There is also the Muslims inrica and Spain (rarely). There is a new enemy that will be have to be dealt with, through, the Magyars.
The Caliphate starts off with relativly similar stats to you, it is large, and powerful. Though you will notice that thy have a extremly smaller levey then you, THIS WILL CHANGE. DO NOT declare war on them as soon as your done fighting in SIcily, as they usually can rais a levy equalling your power, (although a little bit less). In additiion to that, you may notice, that as one of the great rulers of the Arabian empire, this emporer has claims on every muslim kingdom, and will call every sunni leader into a war, if neccessary. Another problem is Jihad, usually this will take place if you or other christian-westren- or even outside forces such as Zorostrians, take charge and start attacking. This is espically prevelant when the Shia uprise, as the Calphiate is responding more to attacks from forigners.
Jihad. the Byzatiine empire has always been a center for attack for the muslims, espically for Anatolia. whicn this will likely happen in your game time, here are a few tips to avanging and defeating them.
Naval combat is key. You are one of the few nations at the start of the world with an advanced navy, that can easily hold all of your troops, the Muslims dont have that, but they do have pleantly of land, the netire Eastern medditerian, that can be attacked. If you constanlly breeze along the coast with your shoips and troops, you can attack quicker then an muslims, , so divide and conquor, attack small armies, quickly, with larger armies. siege, where necessary to hold vital points, that would cause starvation for Muslims is the key for another stratagy that is mentioned later on
Holding the MountiaMiuslim armies should havcve an extremly tough time comeing at you through the Mountianhey have high rates of attritton, in doing so, you have al ine, a line of defence you can guard with armies and generals, through the Mountians, this combined with your Sea tactic, witll create rougly a corner of a square, an ange of defence if you will, that you cannot leaet a single Muslim through.
Defeating the Calphite, is relativly easy though. In a standard war, because you have similar levys the best cource of action is to usually fight a war of attrition, marking how stupidly dumb the AI is at attrition, make sure you lead the enemy winto places it has high attrition, and you dont, such as the mountians, which you own, and are espically hard for armies to travel, meaning they will stay and likely starve as they try to catch up to you. That being said, you will have bonuses if you are defensive in the mountians, and will banish any muslims you have by putting good generals to use with your profesional troops.
My personal facorite time to strike is when the Shia calphiate rises. The shias will usually rise withen a few years after you start form any position in the game, the conditions are almost alyways met, they provide a huge bases to go to war with, usually they rise in the Tuliniud kingomd of Egypt, (which is historically correct in future dates). In the middle of war, taking land from both sides almost always guarntee success.
This will be remake the Byzatine empire in its greatness. where the where they would mainly end up fighting in Asia Minor against Muslim foes, in 867 the main problem looming is Bulgaria, which include parts of Wallachia and Hungary, however, since they are Orthodox, they should not be dangerous and are capable of helping the Empire. In the East, Armenia and Georgia can be vassalized to save them the trouble of facing other states. The Muslims in Sicily and the Middle East are not strong as they were in 1070, so they are not big trouble but they can be if the Caliph is allowed to subjugate them (the Caliphate here is an Empire). With good managing skills, one can control the de jure empire, Bulgaria not included, with parts of the Middle East and Sicily by 900 AD.
The empire is actually one of the more flavorble of starting countries. This is espically true if you have the Legacy of Rome DLC. There are normal, greek-empire to orthodox events (more in Sons of Abraham.)
for the events of Legacy of Rome, which centers mainly around this country in both start dates, you can go to