Advice wanted: 200 Celtic scorpions

The GF and I play on a team, 2v2. Sometimes against people and other times against AI. About 2 games a day. We haven't lost a single game in almost 2 weeks but we got STOMPED today.

We were Franks & Spanish vs. Ethiopians & Celts. We were lucky enough to be next to each other and got a good trade system going. Around the hour mark she (Franks) had the Celts halfway killed, while I finished off the Ethiopians and they surrendered.

Then all hell broke loose.

We got funneled into a stone tunnel and we got hit with 200 scorpions. They took out about 60 paladins in 20 seconds.

We weren't expecting it and by the time we got our second and third waves moving in that direction the Celts left their tunnel and mowed us down.

We were playing on highland and they eventually parked about 100 scorpions outside each of the little walkways we needed to use to access the rest of the map. They wanted to play a battle of attrition.

I used up 40,000 gold and 50,000 food and wood building trebuchets and paladins and eventually trash but we never seemed to make a dent. Eventually we were 4 hours in and used up all the wood on our half of the map so we surrendered. I actually had most units killed by I have no idea what we should've done in that situation.

What would you have done with an army of scorpions picking off your army and trade route?