The recent excavations at Harappa were begun in 1986 by the American team of the Harappa Archaeological Research Project jointly with the Department of Archaeology and Museums of Pakistan. New discoveries and reevaluations of previously excavated areas have contributed greatly to our understanding of this site, which was the type-site of the Harappan (or Indus) Civilization.
The site was inhabited continuously from at least 3300 B.C. until several hundred years after the decline of the Indus Civilization (the "Cemetery H" Culture at Harappa), which represents one of the longest periods of occupation at any Indus site. Recent excavations have focused on the development of the Indus script and the early and late phases of the Indus Civilization at Harappa. (For more details, see the link for "Harappa.com".)

Courtesy of Profs.R.H.Meadow and J.M.Kenoyer (Harappa Archaeological Research Project)