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There's a bit of confusion over terms here. The culture that was first excavated at Harrapa, as per the idiom of archeologists, was named "Harrapan" after the first archeological site at which it was discovered. Historians and archeologists aren't always on the same page, so once it was discovered to be literate, a lot of historians preferred to call it "The Indus Valley Civilization", after the area the culture covered.
In short, archeologists use the word "culture" to describe a coherent set of similar artifacts and other associated leavings. Historians (usually) use "Civilization" to describe a literate culture.
Whatever you call it, the earliest incarnation of this specific culture goes back to about 3300 BC, or about 5000 years ago.
However, this was not the earliest culture to develop anywhere in the Indus river valley. Archeologists found another farming ("Neolithic") culture far upriver at Mehrgarh (in modern day Balochistan, Pakistan). Its artifacts are dated from about 7,000 BCE to about 2500BCE. Judging by the artifacts produced, its a different culture, but it wouldn't be unreasonable to assume the later IVC borrowed elements from it. Particularly its domesticated plants. It was in fact a contemporary of the IVC in the latter's early days.
So if you equate "Civilization" to farming domesticated crops (what we call Neolithic people), then it would be fair to say that was happening in the Indus River Valley about 9,000 years ago.*
Most historians prefer their "Civilization's" to be literate. By that definition, the area qualified from about 2,800 to 1,900 BCE. However, after that, as far as we know no native culture on the entire subcontinent was literate until about 300BCE. This new Brahmi script used a scheme similar to near-eastern Semitic scripts (and the culture was in contact with near eastern Semitic traders). There's no indication it owes anything whatsoever to the Indus Valley script.
So to be super technical here, you can say that "cultures" in the Indus Valley go back more than 8,000 years, but (by the most common definition) the "Civilization" that was there lasted only about 1,000 years, then disappeared.
* - By this standard it would be equally valid to say that "New Guinea Civilization is 11,000 years old", even though no culture native to that island had a writing system until modern times.