Complex sentence: The large number of cuneiform clay tablets preserved by these cultures provide an enormous resource for the study of the period and the region's (and the world's) first cities such as Ur are archaeologically invaluable for studying the growth of urbanization.
Split into simpler sentences: The large number of cuneiform clay tablets preserved by these cultures provide an enormous 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.