I agree with your agreement...
We agree to agree to be in agreement.
At one time what we now know to be the Mediterranean Sea was just a wee pond. Around it existed thousands of villages. Then one day the Strait of Gibraltar opened up and flooded the basin and drowned all the wee village villagers almost overnight. I don’t know if it also rained a lot. But it became a sea. Maybe a local zookeeper had a big boat.