of comparable size have been found anywhere in the Garagum. is also important for the vast amount of numismatic evidence it has revealed; an unbroken series of Sassanian coins has been found there, hinting the extraordinary political stability of this period. Even after the foundation of Soltangala by Abu Muslim at the start of the Abbasid dynasty, persisted as a suburb of the larger Soltangala. In are concentrated many Abbasid-era "industrial" buildings: pottery kilns, steel, iron and copper-working workshops and so on. A well-preserved pottery kiln has an intact vaulted arch support and a square firepit. seems to have been the craftsmen's quarters throughout the Abbasid and pre-Seljuk periods. Soltangala Soltangala (from "Sultan Qala", the sultan's fortress) is by far the largest of Merv's cities. Textual sources establish it was Abu Muslim, the leader of the Abbasid rebellion, who symbolised the beginning of the new Caliphate by commissioning monumental structures to the west of the walls, in what then became Soltangala. The area was quickly walled and became the core of medieval Merv; the many Abbasid-era köshks (fortified building) discovered in and outside Soltangala attest to the centuries of prosperity which followed. Kushks (Persian, Kushk, "pavilion", "kiosk"), which comprise the chief remains of Abbasid Merv, are a building type unique to Central Asia during this period. A kind of semi-fortified two-story palace, whose corrugated walls give it a unique and striking appearance, köshks were the residences of Merv's elite. The second storey of these structures comprised living quarters; the first storey may have been used for storage. Parapets lined the roof, which was often used for living quarters as well. Merv's largest and best-preserved Abbasid köşk is the Greater Gyzgala (Turkmen, "maiden's fortress"), located just outside Soltangala's western wall; this structure consisted of 17 rooms surrounding a central courtyard. The nearby Lesser Gyzgala had extraordinarily thick walls with deep corrugations, as well as multiple interior stairways leading to second storey living quarters. All of Merv's kushks are in precarious states of preservation. However, the most important of Soltangala's surviving buildings are Seljuq constructions. Seljuq leader Toghrul's conquest of Merv in 1037 revitalised the city; under his descendants, especially Sanjar, who made it his residence, Merv found itself at the centre of a large multicultural empire. Evidence of this prosperity is found throughout the Soltangala. Many of these buildings are concentrated in Soltangala's citadel, the Shahryar Ark (Persian, "the Sovereign's citadel"),