Before the Sahara became a desert, it was home to many savanna animals, including the giraffe. People began to paint and etch the Sahara's animals in desert rock about 12,000 years ago. Archaeologists estimate that the oldest remaining pictures date back to 6500 B.C.

By looking at paintings and etchings created thousands of years apart, we can see how life changed as the Sahara slowly became a desert.

These giraffes are reproduced from paintings in a place called Tassili-n-Ajer in Algeria. About 4,000 paintings and etchings can be found on the eroded rocks of this area today.

Catfish swim in paintings from about 5000 B.C.

Catfish, hippos and other water-dependent animals lived in wet areas that later became part of the Sahara. Bones found in long-dry riverbeds and pictures painted or carved on rocks are the only traces of these animals.

In later paintings, chariots cross the Sahara

Paintings from 1200 B.C. show horse-drawn chariots carrying women and men. Sometimes these riders bear weapons; they may have been traders, invaders or both.

Camels appeared about 100 B.C.

As the Sahara became drier, chariots were no longer practical. Sand clogged chariot wheels, and horses needed more water than could be found. Camels, which were better suited to the new climate, replaced horses in pictures of Saharan life.