Seeing this post with a map of Alexander the Great's conquests made me curious: why is it entirely to the east of his homeland? Was there nothing worth conquering in the rest of Europe at the time?
I answered this question a while ago here.
To add to /u/Iphikrates' past answer, there are some reasons to be somewhat sceptical of the Panhellenic motivation behind Alexander's conquests, which I cover here.