The fact that the Djinn are from Djinnjago seems to imply that, in-universe, “-jago” is actually a suffix that can be applied to a people to denote a realm of origin.
This itself then leads to the thought that Ninjago is not, in fact, named for “ninja” like it is in the real world. Instead it lends credence to the idea that, whether or not they are still known as such, the people that call Ninjago home may have been known as “Nin” at one point in time.
Thanks for coming to my stupid “trapped at work” thought ramble















