Using clay bricks made from river mud, they began to build multi-storied homes and temples.

他们用河泥制成的粘土砖开始建造多层房屋和寺庙。

Those clay bricks gave rise to the world's first cities, probably around 4500 BCE. At the top of the city's social ladder were priests and priestesses, who were considered nobility, then merchants, craftspeople, farmers, and enslaved people.

这些粘土砖造就了世界上第一批城市。 大约在公元前 4500 年，在城市社会阶梯的顶端是祭司和女祭司， 他们被认为是贵族， 然后是商人、工匠、农民和奴隶。