It depends what you mean by “Aryan invasion”. The old fashioned view was that self-titled Aryans from Central Asia invaded the Harrapa civilisation in a relatively short period of time and that this was a violent insurrection that destroyed the Harrapa people and essentially replaced them with these foreign Aryans. Under this view the Harrapa civilisation ended mainly because of foreign interference.

However, that view is now thought to be inaccurate. There is plenty of archaeological evidence that there was the emergence of an Aryan culture and that they were probably of Central Asian extraction. So it is not necessarily in dispute that there was a migration from Central Asia. However, unlike the invasion theory the gradualist migration theory is that these Aryans settled in Harrapa over a long period of time and introduced new literature, traditions and culture etc. This led over time to a blending of Harrapa culture and this Aryan culture.

The gradualist theory also supposes that Harrapa was abandoned slowly over time due to a range of factors mostly to do with environmental threats such as flooding, droughts, crop failures etc. Eventually the Harrapa / Aryan descendants resettled further inland closer to modern day India. This would have happened over a long period of time.

You can actually see the blending of these two cultures in the fact that there are Harappa icons that look like Shiva icons so we can trace Shiva back to the Harappa rather than the Aryans which is quite interesting. Also, it seems that Harrapa invented bathing rituals which is so important in later Hinduism. Of course, Vedic Sanskrit and also many more familiar religious concepts are thought to have been of Aryan invention. But the point here is there is quite a bit of evidence of blending leading a lot more credence to the gradualist thesis.

Also there is not much evidence of all out warfare between Aryans and Harrapa though there is a little evidence of imported weapons of war such as chariots. So there may have been the odd out break of violence but not the massive slaughter supposed by the invasion theory.

There is a very long and important book called The Quest for the Origins of Vedic Culture by Edwin Bryant that goes into much more detail. Also An Introduction to Hinduism by Gareth Flood has a nice little section that summarises the main points of this theory in context to the development of religion in India (which is the area I am coming at this from mostly).