[Moltke]

I can’t recall why in the UK, and Europe for that matter Middle Eastern people are referred to as “Asians”.

First, this seems to be a purely British usage. Never heard it elsewhere in Europe.

Second, look at a world map of the continents. Asia stretches all the way west to Africa. Yes, even the Middle East is "Asia".

[DuncanWaring]

Asia - everything west of the Bosporus.