While the Indus Valley Civilization (IVC) has left a vast material record, its internal social structure and political history remain "silent" due to the undeciphered script. This research, the fourth in a series, applies a Reverse Archaeology methodology to the "Old" stratum of the Rigveda (identified in Paper 1 and Paper 2) to reconstruct the lost narrative of the IVC core. Key Technical & Historical Findings: Enemy Profiling (Dasa vs. Dasyu): Quantitative analysis reveals that the "Old" Rigveda's primary adversaries—the Dasa—are described as an organized, urban, and fortress-dwelling rival. This contrasts with the "New" stratum's Dasyu, who are defined by cultural and linguistic alienness. The Shambara Narrative: We track the "Fortress Demon" Shambara across the stratigraphic gradient. The data shows he is 3.4x denser in the archaic mandalas and vanishes entirely from the later strata (Mandalas 8, 9, 10), matching the abandonment of fortified sites in the Late Harappan transition. Urban Reversal: By analyzing the "Enemy" descriptions, we reconstruct the Vedic composers' view of Harappan infrastructure, including complex fortifications (pur), 99-gated strongholds, and the strategic control of riverine resources. Conflict as Data: The paper argues that the Rigvedic "War of Ten Kings" and inter-tribal Vedic conflicts represent the rural-urban friction between the Vedic pastoralists and the urban powers of the Indus core. Conclusion: The Rigveda acts as a "mirror," preserving the descriptions of a civilization that the Vedic people observed, interacted with, and eventually superseded. This paper provides the first systematic attempt to read the Dasa vocabulary not as mythology, but as a contemporaneous eyewitness account of the Mature Harappan urban world.
Tarak Parikh (Wed,) studied this question.