It might be very interesting to compare the history of Hellenistic realms. Most of them had been conquered by Romans so Hellenistic culture remained in Egypt, Syria, Macedonia and everywhere on Roman Empire territory. But there was, for example, Baktrian kingdom blossoming at the times of Demetrios the Great. Greek cities were founded even in India at that period. But finally Bactria was defeated by Kushans. And now - what I know about Greeks in Central Asia? I've seen only few coins with Athena.