Huge World Map (Noyyau'd), 3.72 "c" (manual hotfix) + my own little tweaks.
Egypt, Emperor, Realistic speed. Revolutions on (still nothing of note happened). Leader change active. AI Plays to Win active. Victories active: Conquest, Space, Time.
Ancient and Classical history:
https://forums.civfanatics.com/threads/realism-invictus.411799/page-673#post-16827520
The time is now Turn 900, which would like to be the year 1180 AD , though the tech level began surpassing RL history some time in the medieval era. Emperor-bonus AIs research quite fast.
First some history:
The Medieval era was marked by two very long wars against Rome.
In the 1st the Romans sent huge stacks of Medium Cavalries a very long way around the Caspian Sea, through Bactrian territory, as Armenia didn't have Open Borders with Rome, having recently lost a war against them. Most of the battles were fought near Babylon and in the mountains along the border with Bactria.
Conquered those two cities in Lebanon-Syria (former Mesopotamian, Roman conquered), expanded along the coast up to India to eliminate the last remnant of Arabia, stayed there for the luxury resources.
In the course of the 1st Roman War no one attempted any naval invasion, me for lack of troops (or rather, lack of economy to pay for both defensive troops in Mesopotamia and an expeditionary force at the same time), the Romans… who knows. It had been a tempting idea, a sudden siege of Rome would have been interesting.
During this 1st Roman War, Egypt realized the need for a sizeable heavy cavalry force, as slow moving infantry was not able to deploy quickly enough where needed, now that the Empire was much larger than in the past.
Good thing then that Baibars can build Knights without Feudal Aristocracy! And Late Horse Archers with Flanking II and III are a nice complement to them.
There were also many minor engagements which I won't detail here. A couple of the more notable were the conquest and subjugation of Sahel/Mali (conquering most cities, Capitulation, then "liberating" them back for a Friendly vassal, though quite a useless one as it later turned out), and the eviction of the Scandinavians from the Persian coast (they had contributed to Persia's demise earlier), so that Egypt could have contiguous borders from Mesopotamia to India.
After the end of the 1st RW, Armenia peacefully vassalled to Egypt, having lost a few cities to Bactria in the recent past, though under such cultural pressure that soon after one revolted back, and the other two have massive garrisons to stave off the revolts. Though with Emperor bonuses, I guess it's not much of an economic problem for Bactria.
A few images of the 1st Roman War:
The 2nd Roman War was fought mostly in Armenian territory, to liberate the cities lost to the Romans prior to the 1st RW. It was also the occasion to eliminate the last remnant of the exiled Mesopotamians in Crimea and the last remnant of the exiled Persians in India.
The bulk of the war was a careful campaign with Sentry Horse Archers for scouting, careful sorties with Knights, aggressive road building in Armenian territory and General-supported healing in Armenian cities, leading to victories in "Ukraine". This area has been so constantly fought over in this game, that no one has any real claim to the place (each tile has 5-10% culture from 10+ civs).
And then!
On a whim, sent a scout HA towards "Petroburgum" (former Russian capital), was amazed by the minimal garrison, marched up all available Knights, and despite sorely felt losses, conquered it to discover an incredible 3 (THREE) settled Great Scientists!
The conquest of Petroburgum gave me Arquebuses, ushering in the Reneissance for Egypt, and a change of leader to Ptolemy Soter (Phi,Hum), who promptly renamed everything more "Hellenistically" (I rename all the cities at era/leader change, it's quite immersive), and decided to end the war (the Romans enthusiastically accepted). Thus begins a long Golden Age.
Minor events during the 2nd RW were forays into Europe (Hungary being a Roman vassal at the time), the Bactrian conquest of Poland, the demise of the Scandinavians (who, unbeknownst to me, had already been decimated by the Celts/Scots, who now own the whole of Britain and Scandinavia).
Images of the 2nd Roman War: