What is "margiana"

Margiana ( Margiane, Old Persian: Marguš, Middle Persian: Marv) was a region within the Achaemenid satrapy of Bactria, and a province within its successors, the Seleucid, Parthian and Sasanian empires. After the fall of the Sasanian Empire, Margiana became a quarter of the Umayyad, and later Abbasid, province of Khorasan.

It was located in the valley of the Murghab River which has its sources in the mountains of Afghanistan, and passes through Murghab District in modern Afghanistan, and then reaches the oasis of Merv in modern Turkmenistan. Margiana bordered Parthia to the south-west, Aria in the south, Bactria in the east and Sogdia in the north.