During last few years, three seasons of excavations at the Ultan Qalasi, one season of stratigraphy in Nadir tepesi and a short season of survey in Mughan Steppe enriched our knowledge about the ancient landscape of the area. The Mughan Steppe is a geographically diverse region in the northwestern corner of the Islamic Republic of Iran, defined at the north by the Aras (Araxes) River and including the broad plain to its south as well as the foothills east of the Qara Su river leading up to Mount Sabalan in the Ardebil region. Since the closure of the Russian-Iranian frontier in 1884, the southwestern third of the plain falls within Iran and the northeastern two thirds are within the Republic of Azerbaijan. Since the early 18th century it has hosted the winter camps of the Shahsevan tribal confederacy, who migrated annually between pastures in Mughan and on the slopes of Mount Sabalan.
Already by the time of Shapur I, Mughan was known as Balasagan and was incorporated within the Sassanian Empire. Epigraphic documentation for settlement in Mughan in the Sassanian era is rather sparse. But archaeological surveys in western Mughan Steppe and eastern Mughan and Mil Steppe in Azerbaijan show that there are lots of Sassanian sites, mostly of the fortified type along ancient canals. These evidences indicate intensive land use by the Sassanian state. Previously, large and intensive land use with irrigation canals by Sassanians have been studied in Diyala, southern Mesopotamia and Khuzistan. The Mughan and Mil Steppes present another Sassanian landscape, in this case on the northwestern frontier. The collapse of the intensive Sassanian irrigation system created a void on the steppe which was eventually filled by pastoral nomadic groups.