At first I thought league lacked Asian characters...

Yah I guess. Ionia = asia

The real thing they're lacking is black/dark-skinned characters. There's and maybe , and

Not sure if you can tell if zed is asian.

And all except Karma of them are (or used to be) insanely broken.

Udyr and Kennan are not from Ionia.

Malzahar is not black (his original was closer to either white or "arab", people claimed black because of the in game textures on his fingures). Syndra is absolutely Asian, and Karma is a dark skined Asian.

Lucian is currently the only black champion as far as I am aware.

Ionia is the Runeterra's equivalent to Asia.