What you must know is that this achievement CAN’T be obtained playing FREE BUILD!
I suggest doing other achievements first. If you didn’t got them playing campaign/kingmaker/simulation then there is easy way to get them.
First you must create map for Kingmaker. You must create small estate for enemy AI (make sure it’s small enough to contain ONLY enemy keep), then add some resoruces. Start playing and create stable city. Increase game Speed and leave it running until you get it.