According to new archaeological data, the oldest levels of occupation in Bukhara can be dated to the 5th-2nd centuries BC. During this period, Bukhara consisted of a citadel (arg; ca. 2 ha) on a hill and a large and extensive district beyond a moat to the east. Around the 3rd century BC. BC, the citadel was reinforced with walls up to 6-7 m thick. At the end of the first millennium BC. B.C. and in the centuries immediately following, Bukhara was an autonomous territory within the domain of the K'ang-chü dynasty; its rulers bore the Aramaic title MRʾY "ruler" and minted coins modeled on the tetradrachms of the Bactrian king Euthydemos (d. ca. 189 BC), with a gradual evolution of both the image and inscription.