The Indus Valley Civilization (IVC), one of the largest Chalcolithic civilizations, has posed a significant linguistic puzzle. While various languages are spoken in the IVC region today (Indo-Aryan, Dardic, Iranian, Nuristani, Dravidian, Brahui, and Burushaski), determining the languages spoken during the IVC era is challenging due to the undeciphered Indus script. Archaeological and linguistic arguments have been presented for Proto-Indo-Aryan, Proto-Dravidian, and Proto-Austroasiatic affiliations, with differing scholarly opinions. Archaeogenetic studies, while inferring a genetic signature for IVC people and suggesting possible Proto-Dravidian spread, have not definitively identified the dominant linguistic group. This study aims to address this gap by establishing the existence of ancestral Dravidian languages in the IVC using a multidisciplinary approach, focusing on words meeting specific criteria: historical and linguistic evidence pointing to IVC origins, archaeological evidence showing prevalent use in the IVC, traceable etymology to a South Asian language group, historical and linguistic evidence of presence during the IVC era, archaeogenetic data supporting genetic links to IVC populations, and etymological connection to stable, non-borrowable basic vocabulary. The study focuses on the words 'piru'/'piri' (elephant/ivory) found in Akkadian and Old Persian texts, hypothesizing that their origins lie within the IVC, given its trading relationships with the Near East and the absence of etymological connections to other potential sources of ivory.

The author reviews various scholarly works that attempt to address the linguistic identity of the IVC. This includes the differing views regarding the possibility of the IVC speaking Proto-Indo-Aryan, Proto-Dravidian, or Proto-Austroasiatic languages. The limitations of using archaeological and linguistic evidence alone are highlighted, emphasizing the lack of a deciphered written record and the complexities of prehistoric language distribution. The role of archaeogenetics in reconstructing linguistic pre-history is discussed, noting recent studies that point towards a genetic signature of IVC people and the possible spread of Proto-Dravidian from the IVC to South India. However, the existing genetic data does not provide conclusive proof of the dominant linguistic group of the IVC. The author points out the complexities of correlating genetic ancestry and spoken language, and also the uncertainties surrounding the prehistoric spread of major linguistic groups in the Indian subcontinent.

This interdisciplinary study uses critical analysis of archaeological, historical, linguistic, and genetic evidence to establish the presence of ancestral Dravidian languages in the IVC. The methodology involves identifying proto-words meeting six criteria: (i) historical and linguistic evidence of IVC origin; (ii) archaeological evidence of prevalent use in IVC; (iii) etymological tracing to a South Asian language group; (iv) historical and linguistic evidence of the language group's presence in the IVC era; (v) archaeogenetic data proving genetic links to IVC populations; and (vi) etymological relation to stable, non-borrowable basic vocabulary. The study focuses on the analysis of ancient Near Eastern texts to find fossilized foreign words of possible IVC origin, assuming that imported goods were often referred to by their foreign names. This approach led to the identification of 'piru'/'piri' and their variants as significant proto-words.

The study finds that the Akkadian and Old Persian words 'piru'/'piri' (elephant/ivory) are etymologically related to the Proto-Dravidian tooth-word *pal* and its variants ('*pīl'/'*pil'/'*pel'). The analysis traces the usage of 'piru'-based words across various Mesopotamian and Persian texts, dating back to the Old Babylonian period (ca. 2000-1600 BC), overlapping with the later phases of the IVC. The study argues that given the abundance of elephant ivory in the IVC and its role in trade with Mesopotamia, the 'piru' words were likely borrowed from an Indic source, most likely the IVC. Archaeological and textual evidence supporting the IVC origin of Mesopotamian ivory is presented, including the examination of ivory trade with Magan and Dilmun. The absence of indigenous elephants in Mesopotamia, Persia, and the Persian Gulf, contrasted with the abundance of elephant ivory in the IVC, further strengthens this hypothesis. The study details the connection between the Proto-Dravidian tooth-word and Dravidian elephant words ('pīlu', 'pillakā', 'palla', 'pella'), highlighting the semantic link between 'tooth' and 'elephant tusk'. An analysis of the use of 'pīlu' as a phytonym for *Salvadora persica* (toothbrush tree) further supports the connection between 'pīlu' and the Proto-Dravidian tooth-word. The wide usage of 'pīlu' across different Indic languages and its connection to the IVC regions are presented as evidence. The study emphasizes the importance of 'tooth' as an ultraconserved vocabulary item, a key element in tracing deep linguistic ancestry and pointing towards the presence of Proto-Dravidian speakers in the IVC.

The findings suggest that the use of a Proto-Dravidian tooth-word by a significant portion of the IVC population points to the presence of ancestral Dravidian languages in the civilization. The study's conclusion that Proto-Dravidian was spoken in the IVC aligns with recent archaeogenetic findings regarding the migration of Proto-Dravidian speakers from the Indus Valley to South India. This supports the hypothesis of a significant population of IVC speaking Dravidian languages. The discussion also addresses alternative hypotheses, such as the possibility that Proto-Dravidian originated in South India rather than in the IVC. The study acknowledges the limitations of solely relying on linguistic evidence and suggests that further multidisciplinary research combining linguistic, archaeological, and genetic data is necessary for a complete understanding of IVC languages. This study also discusses the Brahui language and its genetic links to IVC populations to further reinforce the evidence for Proto-Dravidian in the IVC.

This study presents strong evidence for the presence of ancestral Dravidian languages within the Indus Valley Civilization. The analysis of the ultraconserved Proto-Dravidian tooth-word *pal* and its cognates in words related to elephants and the toothbrush tree, combined with archaeological, historical, and genetic evidence, supports this conclusion. Future research should focus on further analysis of the Indus script, potentially revealing more direct linguistic evidence. Additional archaeogenetic studies would further clarify the migration patterns and linguistic shifts in ancient South Asia. Investigating the relationship between other ultraconserved words and their distribution in IVC could also provide further insights.

The study relies heavily on etymological analysis and interpretation of ancient texts, which can be subjective. The undeciphered Indus script prevents direct confirmation of the presence of Dravidian languages. While archaeogenetic studies provide supporting evidence, they don't definitively establish linguistic affiliation. The study focuses on a single vocabulary item and its related derivations, limiting the breadth of the linguistic analysis. The study acknowledges these limitations and emphasizes the need for further multidisciplinary research to fully address the complexity of IVC languages.