What is "demetriapolis"

Demetriapolis, or Demetrias was a Greek city in Arachosia, thought to have been founded by the Greco-Bactrian king Demetrius as he invaded areas south of the Hindu Kush. In the 1st century BCE in his "Parthian stations", Isidorus of Charax mentions the rule of the Parthians over Arachosia, an area south of the Hindu Kush and next to today's Afghanistan, and populated by Greek colonies:

"Beyond is Arachosia. And the Parthians call this White India; there are the city of Biyt and the city of Pharsana and the city of Chorochoad and the city of Demetrias; then Alexandropolis, the metropolis of Arachosia; it is Greek, and by it flows the river Arachotus. As far as this place the land is under the rule of the Parthians." "Parthians stations", 1st century BCE