The Sumerians are thought to have formed the first human civilization in world history. They lived in southern Mesopotamia, between the Tigris and Euphrates Rivers in the Middle East. Cradle of Civilization. Many historians think that cities and towns were first formed in Sumer around 5000 BC.
At noon, on March 21 and September 23rd are the vernal and autumnal equinoxes. The sun is directly overhead at the equator at these times. On June 22nd is the summer solstice, in the Northern Hemisphere. The sun is at the 23.5 degrees Northern latitude.
So the date of June 20/21 would be the summer solstice for people living in the northern hemisphere, and the winter solstice for those in the southern hemisphere, and vice versa on December 20/21. This is the day of the year where the sun is at the highest point over the Equator, so the farthest north.