India has extensive archaeological remains that are among the largest and oldest in the world. Harappan India or India of the so-called 'Indus Valley Civilization' was the largest urban civilization in the world of its times in the third millennium BC (3100-1900 BCE), with major sites extending from the Ganges river in the east to Afghanistan in the west, from the border of Iran to near Bombay. However, India's role in ancient civilization has been largely ignored in favor of more culturally comfortable, though geographically much smaller cultures in the Near East, in spite of the fact that such ancient cultures frequently lauded the greatness of India themselves. How many of us know that the civilizations of Egypt and Mesopotamia would fit easily into Harappan India with much room to spare, so much larger was the Indian civilization. There has been an even greater ignoring of the Vedic literature of India, which is by far the largest that has been preserved from the ancient world.
Some say the Rig Veda was brought to India by the Aryans.
Oh, that's plain misinterpretation. The Rig Veda speaks of the Saraswati river as the homeland. And geological records now show that the Saraswati was the largest river in India before 2000 BC, going back at least 5000 years before that. There are many other factors. Harappan sites display swastikas, yagyashalas (Vedic fire ritual sites), and figures sitting in meditation. I think the gap between Vedic records and archaeological records exist more in the mind of the western scholars. Landsat photography from outer space showed that there was once a Saraswati river.
Was this pre-Indus Valley civilization or post?
There were several Vedic ages; the Harappan period was part of the late Vedic age. You have to understand that the Vedas are a recordójust one book as the record of the culture. If you had only one book preserved from the modern world, it would not represent all the cultures, all the people and every aspect of it. It represents a major trend within that society, but you can't make it exhaustive.
The Myth of Aryan Invasion