How do we know about the early civilizations?

Early civilizations arose first in Lower Mesopotamia (3000 BCE), followed by Egyptian civilization along the Nile River (3000 BCE), the Harappan civilization in the Indus River Valley (in present-day India and Pakistan; 2500 BCE), and Chinese civilization along the Yellow and Yangtze Rivers (2200 BCE).

Explanation:

Civilization describes a complex way of life that came about as people began to develop networks of urban settlements. The earliest civilizations developed between 4000 and 3000 BCE, when the rise of agriculture and trade allowed people to have surplus food and economic stability.

Answer: We knows about the early civilixation because in caves there is writing. Also there is remains or ruins of early civilizations such as the Indus Valley civiliaztion.