Assyriology (from Greek Ἀσσυρίᾱ, Assyriā; and -λογία, -logia) is the archaeological, historical, and linguistic study of ancient Mesopotamia (essentially ancient Iraq and some areas of northeastern Syria and southeastern Turkey) and of related cultures that used cuneiform writing. The field covers the Akkadian sister-cultures of Assyria and Babylonia, together with their cultural predecessors, Sumer and the Akkadian Empire. The large number of cuneiform clay tablets preserved by these cultures provide an extremely large resource for the study of the period. The region's (and the world's) first cities such as Ur are archaeologically invaluable for studying the growth of urbanization.