I don't know how often the AIs make an offer in this version, but I'm likely to deny it anyway: I came to finish them. I usually play with one ally and four enemies, if you team them up it becomes harder; with three teams in total there's decent variability in how they behave.

https://warfare.6te.net/Ancient/Shield-Dura-Europos-Yale.htm 38. Shield or mantlet of reeds, late 3rd century AD, Sassanian (?), Dura-Europos, Yale University Art Gallery, New Haven (Mes, Brow A). Vol. 1, p235: Shields made of reed or cane had been used in the Middle East since pre-historic times. A magnificently preserved rectangular Sassanian example was excavated at Dura Europos (Fig. 38). Comparable shields may well have been used in Persia and Iraq until the time of the Muslim conquest,26 but whether the reed shields of pre-Islamic Arabia27 Syria: The ark is captured by the Philistines at the Battle of Even ha-Ezer. Fresco from Dura Europos.

Make sure to try Neutral first, and not after you've killed any of their units. They're less likely to agree to neutrality if you've killed a bunch of their units.