I'm having a similar situation.

I'm playing in the English (H/H), and it is about turn 120. The Mongols appeared a few turns ago north of Edessa. At the time I controlled Antioch, Acre, Damascus, Gaza, Jerusalem, Alexandria and Cairo.

Anyway, I moved my strongest Army in the Middle East to block the bridge that leads to Antioch. My second Army blocked the river crossing to the east of Antioch.

For a couple turns they just stood there northwest of Edessa. Then the Council of Nobles gave me a mission to capture the rebel-held province of Aleppo. I was afraid that such an attack would make me too vulnerable to the nearby Mongol armies, but after they pattered about the foothills of Edessa for another couple turns I moved on Aleppo and captured it.

Seemed that this enticed the Mongols to chase me, and I was forced to abandon Aleppo the turn after I captured it, and fall back to my original positions.

The Mongols kept coming and ended up sending two full stacks at the river crossing. I held, but was forced off by the third stack. When I successfully defended the hills east of Antioch against that third stack, the Mongols pulled back to their original position north of Edessa.

They are there again, while I too have fallen back to having my two armies protecting the river crossings into Antioch. And now we are just staring at each other across the desert again.

I'm not sure why this is happening. I think the Mongols definitely want to capture Antioch, and I don't know why they aren't coming. They would take severe casualties to break through my defenses, but from the multitude of stacks they have sitting out in the desert it looks like they could out-muscle me and overrun Antioch for sure.

If they attacked with strength I have no doubt they would capture Antioch and Damascus for sure. Acre would probably also fall.

But I'm happy they are not. I'm reinforcing my defenses in the Holy Land, and the relative peace has allowed me to expand my empire elsewhere. I had just defeated the French before going to bed last night.