The prosperous and flourishing civilization of Indus Valley was brought to an end by the savage invasions of the Aryans about 1,500 B.C. These warlike nomads had encountered a very sophisticated civilization that of the Indus Valley. Large number of skeletons discovered in Harappa, Meonjo Daro and other places shows that the local people put up stiff resistance and died fighting valiantly. There are traces of widespread devastation caused by the invaders in the entire Pakistan. A scorched earth policy seems to have been followed which extinguished almost all traces of civilization in the region. “Evidence from Baluchistan, Sind and the Punjab is reasonably consistent in implying that at some period likely to have been before 1,500 B.C., to use a convenient round figure, the long established cultural traditions of north-western India (i.e., Pakistan) were rudely and ruthlessly interrupted by the arrival of new people from the West. The Aryan advent was in fact the arrival of Barbarians into a region already highly organized into an empire based on a long established tradition of literate urban culture.
“In the hymns of the Rigveda, the invasion constantly assumes the form of an onslaught upon the walled cities of the ‘aborigines’…… It is not indeed impossible that the name of Harappa itself is concealed in the Hari-Yupia which is mentioned in the Rigveda as the scene of a battle.” (Early India and Pakistan to Ashoka, By Sir Mortimer Wheeler)
However, the Aryans during their stay in Pakistan picked up much from the Indus Civilization which stood them in good stead during their settled life in India. “Aryans entered and Aryanized the middle country of the Ganges Doab after picking up ideas of craftsmen in the Indus Valley and the Baluch borderland.” (Ibid)
According to some authors Chandragupta Maurya and his dynasty were the ghosts of the Harappa Empire. “To the complex pattern of the Indian Middle Ages the ancient urban civilization of the Punjab and the Indus surely contributed not a little. And this was a contribution not only in the sphere of religious speculation or in traditions of ritual and ceremonial observances: The whole character of medieval Hindu society and the structure of its polity and government seem inevitably a reflection of the civilization of Sind and the Punjab. (Ibid)
Some modern historians even link the great Ajanta art to the Indus Valley Civilization because “the Vedic Hindu culture which prevailed before the Buddhistic culture in north India is not known to have had any painting worth the name.” (Indian Culture, By S. Abid Hussain)
The Aryan tribes which occupied Pakistan have been identified as Sivas, Parsas, Kayayas, Vrichivants, Yadus, Anus, Turvasas, Dratyus and Nichyas. The Sivas Aryans had their capital at Sivistan which is supposed to be modern Sehwan.
“It may be of interest to mention here that so long as the Aryans stayed in Pakistan, they did not evolve that particular religion called ‘Hinduism’ with its caste system and other taboos. It was only when they crossed the Sutlej and settled in the Gangetic Valley that this abominable system was evolved. “While settled in the Punjab the Aryans had not yet become Hindu…. The distinctive Brahmanical System appears to have been evolved after the Sutlej had been passed. To the east of Sutlej the Indo-Aryans were usually safe from foreign invasions and free to work out their own rule of life undisturbed. This also explains the absence of Hindu holy cities and temples in Pakistan.”
“The castes were hardened by the time the Aryans occupied the middle land i.e., the Gangetic Valley and distinguished themselves from their bretheren in Sind and the Punjab who were despised by them for not observing the rules of caste …. and for their non-Brahmanical character.” (Sindhi Culture, By U.T. Thakur)
“While the Aryans had by now expanded far into India, their old home in the Pakistan (Punjab, Sind and the north-west) was practically forgotten. Later Vedic literature mentions it rarely, and then usually with disparagement and contempt, as an impure land where the Vedic sacrifices are not performed.”
However, the one redeeming point that emerges from the Aryan occupation of Pakistan for over five hundred years from 1,500 B.C. to 1,000 B.C. is that during this entire period this country again led a separate existence. It had hardly anything to do yet with the rest of the sub-continent and continued the traditions of cultural and political independence inherited from the Indus Valley Civilization. As such, even under Aryan occupation, Pakistan was an independent country separate from India.
“The evidence of the Rig Veda shows that during the centuries when the Aryans were occupying the Punjab and composing the hymns of the Rig Veda, the north-west part of the subcontinent was culturally separate from the rest of India. The closest cultural relations of the Indo-Aryans at that period were with the Iranians, whose language and sacred texts are preserved in the various works known as the Avesta, in inscriptions in Old Persian, and in some other scattered documents. So great is the amount of material common to the Rig Veda Aryans and the Iranians that the books of the two peoples show common geographic names as well as deities and ideas”. (Pakistan and Western Asia, By Prof. Norman Brown)
When the Aryans conquered India and migrated from Pakistan in about 1,000 B.C., the latter country again became independent and did not conform to the system that began to be evolved in the Gangetic Valley by its conquers. Except for the Rigveda, the remaining three Vedas and other religious books of the Hindus such as Upanishads, Shastras, Aranyakas, Brahmanas, the two epics of Ramayana and Mahabharata etc., on which their social and cultural system rests, were written outside Pakistan.
For the next about five hundred years from 1,000 B.C. to 500 B.C. little is known about Pakistan. Many of the Aryans had left this country (and many remained) and the only point clear is that these areas had again become independent, were averse to the religious system evolved by the Aryans in India, leading to a rift between the two. The Aryans were extremely unhappy at this revolt by the people of Pakistan and had begun to despise and abhor them placing them outside their fold.