Inspired by the (classical) Romans vs. Mongol thread, I pose the following questions, how would the Byzantine Empire fare against the Mongols?
To help frame the discussion, I posit the following scenario:
The Macedonian dynasty does not die out in the Byzantine Empire, but is still in existence in the mid 1200s. The Empire's borders have changed little since 1060, except in Italy where the southern third of Italy plus Sicily are in Byzantine hands. The Byzantine army is equal in quality to the army in 1025 and has kept up with technological developments. Outside of the Empire's borders, the world is identical to OTL 1240 (yes, I know it's unrealistic, but a POD in the 900s could butterfly away the Mongol conquests entirely). In that year the Mongols sack Kiev.
How does this Roman Empire fare against the Mongols?