By 4,000 years ago there where very many civilizations in Earth. Most of thees civilization are plastd in the camfortable ground for farming.
For example we can take Crete. Cretes climate has always been vild. Still, Crete has never had as much, rain as the farmers wanted. People comt to Crete across the sea. In that place people building cities.
Crete is very convinient and comfortable. Cretans caught much fish/ There are many sheep, goat and pigs/ They drank goat milk and eat goats cheese/
Cretans lived on in island and new sea, become sailors. They built boats and sailed far from home landing in Egypt and on the coast of Southwes Asia.