An empire with similar characteristics would be the Mauryan empire. I can convince him to join Raja Eisert's empire by telling him that Raja Eisert's also likes to keep track of people in his kingdom.

Raja #1

The Mauryan empire is similar to Raja Eisert because they both have a bureaucracy.

Maurya empire packet page 235

I would tell him that raja Eisert also likes to keep track of people in his kingdom because if raja #1 hears that they are similar, there is a better chance of him agreeing