Babylon in Southwest Asia is at the center of the very earliest world maps, beginning with the Babylonian world map in the 6th century BC; it is a clay tablet 'localized' world map of Babylon, rivers, encircling ocean, and terrain, surrounded by 'islands' in a 7-star format. In classical Greek geography, "Asia" is one of three major landmasses, besides Europe and Libya. Asia is given higher resolution in Hellenistic geography, in particular on Ptolemy world map. Cartography of India begins with early charts for navigation and constructional plans for buildings. Chinese geography from the 2nd century BC (Han dynasty) becomes aware of Turkestan, where Hellenistic Greek and Han Chinese spheres of influence overlap.