(i) The Great Rift valley in Africa has many sites that have evidence for the prehistoric period.
(ii) The Great Rift valley is a valley - like formation that runs for about 6,400 km from the Northern part of Syria to Central Mozambique in East Africa.
(iii) This geographical feature is visible even from the space, and many prehistoric sites are found in Africa

(i) The idea of the Three Age system proposed by C.J. Thomsen became the basis for understanding early human history.
(ii) He classified the artefacts in the Danish National Museum, Copenhagen, into Stone Age, Bronze Age and Iron Age.

(i) The earth was formed approximately 4.54 billion years ago.
(ii) Gradually, conditions emerged for the growth of organisms.
(iii) Then plants and animals came into being and thereby foundation was laid for the evolution of humans.
(iv) The long span of time in earth's history is divided into eras periods and epochs by the geologists.

1. The people in the Iron Age practiced agriculture, domesticated animals.
2. Cattle rearing was an important occupation of these people.
3. They domesticated catHe and sheep.
4. They lived in small villages.

1. In the course of evolution, humans became conscious and knowledgeable.
2. They turned curious and began to think and ask questions.
3. At first, they considered nature as God.
4. They worshipped sun, moon and various natural forces about which they developed their own understanding.

(i) The culture that domesticated animals and cultivated crops is called Neolithic.
(ii) It is known as the New Stone Age. The Neolithic people used polished stone axes called celts.
(iii) Cattle rearing was their main occupation. They lived in small villages with houses made of thatched roof and walls plastered with clay.
(iv) Evidence of Neolithic village is found at Payyampalli in Vellore district and a few sites in the Dharmapuri region.
(v) Payyampalli is a village in Vellore district of Tamil Nadu. The earliest evidence for the domestication of animals and cultivation of plants is found at this site, which was excavated by the Archaeological Survey of India.
(vi) Evidence for pottery making and cultivation of horse gram and green gram has been found in this village.
(vii) These Neolithic sites were part of the Southern Neolithic Culture of India. They are mainly concentrated in the Andhra Pradesh and Karnataka regions.
(viii) The Neolithic people used stone axes fitted on a wooden handle .
(ix) These polished stone axes are worshipped in many village temples of Tamil Nadu even today.

(i) The history of humans is closely related to the history of the earth.
(ii) The earth contains geological, archaeological and biological records of historical times in its upper layers.
(iii) They are important for reconstructing the history of the earth and various living organisms.
(iv) The fossil bones of the human ancestors are embedded in the earth's layers.
(v) Palaeoanthropologists and archaeologists excavate the soil and rock layers on the earth and extract evidence about human ancestors.
(vi) These layers and the fossils are scientifically dated to study the various stages in human evolution and prehistory.
(vii) Through the gathered evidence they attempt to understand the evolution of human history and developments in a chronological order.·
(viii) The earth was formed approximately 4.54 billion years ago.
(ix) Gradually conditions emerged for the growth of organisms. Then plants and animals came into being and thereby foundation was laid for the evolution of humans. The long span of time in earth's history is divided into eras, periods and epochs by the Geologists. Thus the history of humans is closely related to the history of the earth.