I chose the year zero as an arbitrary endpoint in the timeline. A review of the chart shows Mesopotamia leading the way, with Egypt close behind, eventually catching up. China was a couple thousand years behind Mesopotamia when it began, but closed the gap to a thousand years later on. The two civilizations of the Americas were still father behind and did not complete their developmental phases before the year zero.
One can clearly see how the terms the “fertile crescent” and “cradle of civilization” fit Mesopotamia and Egypt as the earliest cultures.