The suffix -stan in Persian

The Persian suffix -stan ـستان‎, [-stân after a vowel, -estân or -istân after a consonant] has the meaning of “a place abounding in” or “a place where anything abounds.” It appears in the names of many regions in Iran, Afghanistan, and Central and South Asia, as well as in the Caucasus and Russia. The suffix is also used more generally, as in:

rigestân (Persian: ریگستان‎) “place of sand, desert,”

golestân (Persian: گلستان‎) “place of flowers, garden,”

gurestân (Persian: گورستان‎) “graveyard, cemetery,” 

Hindustân (Persian: هندوستان‎) “land of the Indus river” (India).

Khuzestan Province (Persian استان خوزستان‎ Ostān-e Khūzestān) is one of the 31 provinces of modern Irān. 

HERE IS A LINK to the Wikipedia page devoted to a century-by-century discussion of this ancient place. Note that it is part of the alluvial plain that drains the Tigris river.