A term used to describe the art and architecture of ancient Greece, which consisted of many independent city states around the Aegean Sea bound together only by a shared language and religion. Alexander the Great, until his death in Babylon in 323 bc, succeeded in imposing a sense of Greek empire and unity in the face of the seemingly perennial threat from the Persians, but this cohesion soon fell apart under his successors. Nevertheless, the artistic achievements of the Greeks were enormously innovative and formed the basis for much of the later art and architecture of the Romans, by whom they were conquered in the middle of the 2nd century bc. Ancient Greek art is divided into three main periods: Archaic (c.700–c.480 bc), Classical (c.480–323 bc), and Hellenistic (323–27 bc). Further sub-divisions have been applied to Greek pottery, the most significant styles of which are Geometric (c.900–c.700 bc), Orientalizing (from around c.700 bc and with many distinct regional schools), black-figure (7th and 6th centuries bc, originating in Corinth), and red-figure (6th century bc onwards).