Why does English have different suffixes for referring to different ethnicities

Question

Like for example, why do we say things like Scottish, Saudi Arabian and Japanese and not things like Japanian, Arabish or Scottese?

Bonus points if somebody can point a reason why a lot of these suffixes are pretty consistent to their world regions? Many European countries refer to their people as ___ish, many Asian countries as ___ese and many Middle Eastern countries as ____ian?

Thanks!!

In: Other

Answer 1

There’s also some that are completely off the wall. Yeah Pennsylvanian or Texan make sense, but a person from Indiana? A Hoosier.

Poor Purdue kids.