This book is quite extensively illustrated (in a mid-60's way), which lets one "armchair travel" to these sites. What is fascinating about the Indus Valley civilization is that it pretty much just appeared about 2,600 BCE with a whole series of cities (one, Harappa has given its name to the culture as "Harappan", but the city itself was the victim of "pragmatic looters", the workers on the railway opted to use the bricks of Harappa as a base for the rails rather than make their own!) along the Indus. These do not appear to have "evolved" in the sense that a city like Paris or London built up from it's smaller predecessors, but arrived fully-grown, with a sophisticated grid system of streets, grain storage facilities, and (most remarkably) an advanced sanitation system of toilets, sewers, and drainage. Needless to say, city planning, advanced engineering, specialized architecture needs to come from somewhere and the lack of evident antecedents to the Indus Valley culture is one of the great mysteries (I had a theory, but it plays more to the writing of John Anthony West than to "standard" archaeology).
The book is, however, only partially about this culture, and it looks at surrounding areas, and then runs the timeline up through the Greek and Persian phases. Wheeler seems to tip-toe around the "Aryan invasion", not being willing to assign specific archaeological finds to this event, but he does note that some rather grisly discoveries (massacred bodies left as they fell) may well be a result of that historical influx, as some of the cities seem to correspond to places mentioned in the (Aryan) Rigveda. There is a bit of a gap between the decline of the Harappan culture (the theory seems to be that there was a seismic event sometime around 1900 BCE which caused significant re-channeling of the rivers and a substantial change in the local climate which led to this downfall) and the arrival of the Aryan tribes, but the fall of the former may well have opened the door for the latter, and residual populations may have still been in the remnants of the great cities by that time.
Remarkably, for a book this old (which is out of print) there are "very good" copies available of Civilizations of the Indus Valley and Beyond via the new/used vendors, for as little as $3.58 (plus shipping). Of course, you might find a copy like I did (on the half-off day at the Newberry), but if you're interested in the subject, this is a very nice, and remarkably readable introduction. As a side note, the copy I got had an "ex libris" stamp in it from a Researcher down at the Oriental Institute at the University of Chicago, which makes me wonder how it ended up at the Book Fair (a lot of their books come from the estates of the recently deceased, and the previous owner, according to the Oriental Institute's web site, seems to be quite extant). Anyway ... if you don't know a lot about Mohenjo-Daro and Harappa, and find the subject of interest, you may want to track down a copy of this book!