Landscapes, soils, and mound histories of the Upper Indus Valley, Pakistan: New insights on the Holocene environments near ancient Harappa

The site of Harappa in central Pakistan has been the primary source of information on Indus Valley cultural and natural landscapes in the Upper Indus Basin. While the site has been excavated for over 100 years, little was known of the pre-occupation history and environments responsible for the culture's emergence in the third millennium BC. Recent geoarcheological investigations of sites sharing the same landform as Harappa-the Bari Doab-along the ancient Beas River have synthesized sediment, soil, and cultural stratigraphies that place Harappa in the context of a regional landscape history. Two key sites-Lahoma Lal Tibba and Chak Purbane Syal-illustrate that larger floodplains of the Indus system stabilized sometime in the early Holocene, when soil development exceeded rates of alluviation. The site of Harappa was revisited to procure radiocarbon dates beneath initial occupation horizons. The stratigraphy and dates established the Pleistocene/Holocene interface and confirmed coeval trends of diminished Early Holocene floodplain accretion and sustained soil formation. Pedogenesis continued at least to the beginning of the fifth millennium BP when occupation began to intensify along the Beas and elsewhere in the Upper Indus. Site formation sequences at Lahoma Lal Tibba and Chak Purbane Syal mirror those of Harappa proper, albeit on a smaller scale.