The cities of the Harappan Culture had declined by 1500 B.C. Consequently, their economic and administrative system had slowly declined. Around this period, the speakers of Indo-Aryan language, Sanskrit, entered the north-west India from the Indo-Iranian region. Initially they would have come in small numbers through the passes in the northwestern mountains. Their initial settlements were in the valleys of the north-west and the plains of the Punjab. Later, they moved into Indo-Gangetic plains. As they were mainly a cattle-keeping people, they were mainly in search of pastures. By 6th century B.C., they occupied the whole of North India, which was referred to as Aryavarta. This period between 1500 B.C and 600 B.C may be divided into the Early Vedic Period or Rig Vedic Period (1500 B.C -1000 B.C) and the Later Vedic Period (1000B.C - 600 B.C).
The original home of the Aryans is a debatable question and there are several views. Different scholars have identified different regions as the original home of the Aryans. They include the Arctic region, Germany, Central Asia and southern Russia. Bala Gangadhara Tilak argues that the Aryans came from the Arctic region on astronomical calculations. However, the theory of southern Russia appears to be more probable and widely accepted by historians. From there, the Aryans moved to different parts of Asia and Europe. They entered India in about 1500 B.C. and came to be known as Indo-Aryans. They spoke the Indo-Aryan language, Sanskrit.
The word 'Veda' is derived from the root 'vid', which means to know. In other words, the term 'Veda' signifies 'superior knowledge'. The Vedic literature consists of the four Vedas - Rig, Yajur, Sama and Atharva. The Rig Veda is the earliest of the four Vedas and it consists of 1028 hymns. The hymns were sung in praise of various gods. The Yajur Veda consists of various details of rules to be observed at the time of sacrifice. The Sama Veda is set to tune for the purpose of chanting during sacrifice. It is called the book of chants and the origins of Indian music are traced in it. The Atharva Veda contains details of rituals.
Besides the Vedas, there are other sacred works like the Brahmanas, the Upanishads, the Aranyakas and the epics Ramayana and Mahabharata. The Brahmanas are the treatises relating to prayer and sacrificial ceremony. The Upanishads are philosophical texts dealing with topic like the soul, the absolute, the origin of the world and the mysteries of nature. The Aranyakas are called forest books and they deal with mysticism, rites, rituals and sacrifices. The author of Ramayana was Valmiki and that of Mahabharata was Vedavyas.
During the Rig Vedic period, the Aryans were mostly confined to the Indus region. The Rig Veda refers to Saptasindhu or the land of seven rivers. This includes the five rivers of Punjab, namely Jhelum, Chenab, Ravi, Beas and Sutlej along with the Indus and Saraswathi. The political, social and cultural life of the Rig Vedic people can be traced from the hymns of the Rig Veda.
The Aryans further moved towards east in the Later Vedic Period. The Satapatha Brahmana refers to the expansion of Aryans to the eastern Gangetic plains. Several tribal groups and kingdoms are mentioned in the later Vedic literature. One important development during this period is the growth of large kingdoms. Kuru and Panchala kingdoms flourished in the beginning. Parikshat and Janamejaya were the famous rulers of Kuru kingdom. Pravahana Jaivali was a popular king of the Panchalas. He was a patron of learning. After the fall of Kurus and Panchalas, other kingdoms like Kosala, Kasi and Videha came into prominence. The famous ruler of Kasi was Ajatasatru. Janaka was the king of Videha with its capital at Mithila. His court was adorned by scholar Yajnavalkya. Magadha, Anga and Vanga seem to be the easternmost tribal kingdoms. The later Vedic texts also refer to the three divisions of India - Aryavarta (northern India), Madhyadesa (central India) and Dakshinapatha (southern India).