Q: After Alexander the Great (Hellenistic Kingdoms)

Not quite.  The realms were originally as follows: Antipater and his successors remained in control of Macedonia and Greece(however, Cassander, Antipater's soc, soon asserted himself as Macedonian ruler), Lysimachus ruled Thrace, Antigonus ruled Phrygia and much of Asia Minor, Ptolemy ruled Egypt, and Seleucus ruled the Eastern possessions(Mesopotamia to India).

Hmm, well, several historinas wrote great works on the era.  Arrian wrote a book about the Diadochian wars, but it only survives in fragments.  Diodorus' Bibliotheke is probably the most complete work we have for the era, though some of his sources aren't the most reliable.  Most of Diodorus' info. on the Diadochian Wars comes from Diyllus(who wrote events until 297BC) and Hieronymus.  There was also a writer named Duris who wrote a 'history' of the era, but many say it is more a great display of writing than anything else, and is probably not the most truthful source for the era.

Of course, there are also biographies pertinent to the era in Plutarch's Lives. And there is the likely biased work of Timaeus.

The Graeco-Indian kingdom of Bactria (originally an part of Seleucid holdings, later autonomus but direclty linke to the "highest authority" of the the Seleucid line) didn't outlive the other Greek kingdoms of the East. Actually it succumbed earlier than the Seleucids, but I am not completely sure of the dates, I'll have to look up a source.

It makes for a fascinating story about the mixture of "East" and "West", though.

On the other subjects of this - very interesting - discussion, truth is that the Parthian (Parnii originally) elite as the Pondian and the Thracian elite, was vastly hellenized, although Parni seem to originate from an iranic people. They spoke a form of Greek, and upheld the Greek customs, seing as Greeks in the 3rd century BC were something like Americans of today (or better: English of the 19th century, before the Americans came and settled in their place - in our case Americans=Romans). But that doesn't mean they abandoned any of their nomadic roots. They excelled at horsemanship and archery and kept their tribal organization - evident by the fragmentation of their "empire" and the fact that the seat of power was periodically shifting from settlement to settlement.

Later the Parthians became assimilated by the Persian population and their elite class merged with the Persian elite class that rose again after the Greek and Parthian rule.

I suppose the Sassanids needed to create a sense of nationalistic, distinctively Persian culture amongst its subjects, in order to preserve itself from Roman (and later Greek-Byzantine) aggression.

It would be hard to fight against Greeks while at night you're reciting Greek poetry in symposiums (figure of speech )

None of my readings supports this view. The Parnii are considered of Iranian origin (or Iranic-like) in all sources I've got at my disposal. You got any source stating they were Sacae or Scythic?

I am not sure if the Sacae were Iranians, but if they were they didn't have anything to do with the Skythians - those were definitely not Iranians and we all know that well.

The Iranians are not that wide group of people... except if you are looking for the term "Aryans", but then you'd have to include many, many others under that umbrella

I do not think that you are up to mastering the fine art of sarcasm yet, my friend.

You said that Parnii are Sacae-Skythic

I said that Parnii are Iranian people, not Skythes

You said that Sacae are Iranian and I replied that definitely the Skythes are not even close on having anything to do with Iranians.

So, who doesn't know what he's talking about?

Are many people on this board excessively rude and arrogant as you? Or is it just that you are young and immature and that's the only way you know to express your opinion on something?

Even if you are right on the topic (which I seriously doubt) your rudeness is not really appreciated.