Editing Info:1d5d8211-a482-402f-8cd2-b99a6cb3d1a5 (section)

=== Classification of theories ===

'''A. Plausible explanations''' (supported by evidence, not refuted):
* '''Logo-syllabic writing encoding a Dravidian language''': The sign count, structural properties, and geographic/chronological context are consistent with a logo-syllabic system encoding an early Dravidian language. Parpola's rebus readings, while unverified, represent the most systematically developed decipherment attempt (Parpola 1994, 2010).
* '''Logo-syllabic writing encoding an unknown or language-isolate language''': The underlying language may belong to a family no longer spoken or not yet identified. The Brahui language of Balochistan, a Dravidian isolate in the region, is sometimes cited as a possible relic.
* '''Structured symbolic system with some linguistic content''': The signs may combine linguistic elements (personal names, titles) with non-linguistic markers (clan symbols, commodity indicators), producing a hybrid system that defies conventional decipherment categories.

'''B. Possible explanations''' (raised by researchers, less well supported):
* '''Indo-Aryan or Indo-European language''': Some scholars have proposed that the underlying language was an early form of Indo-Aryan or another Indo-European branch. This hypothesis is chronologically possible but conflicts with the mainstream linguistic chronology, which places the Indo-Aryan arrival in South Asia after the decline of the Harappan civilisation.
* '''Proto-Munda (Austroasiatic) language''': The presence of Munda languages in eastern India has prompted suggestions of Austroasiatic linguistic substrates in the Indus region, but this hypothesis has limited supporting evidence.

'''C. Highly unlikely but argued by some''':
* '''Non-linguistic symbol system''': Farmer, Sproat, and Witzel (2004) argued that the Indus signs are not writing at all but a non-linguistic sign system. This position has been challenged by the entropic evidence (Rao et al. 2009) and by the structured positional distributions of signs, though the debate continues.
* '''Deciphered script''': Multiple claims of complete decipherment have been published, none of which has achieved independent verification or scholarly consensus.

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