[4] Going by attested changes in written documents, the Proto-South Dravidian I (PSD1) language has been hypothesised to have been present in the second half of the first millennium BC.
[4] Proto-South Dravidian inherited the system of five short and long vowels from Proto-Dravidian: *a, *ā, *i, *ī, *u, *ū, *e, *ē, *o, *ō.
[5] Old Tamil, the earliest attested branch of South Dravidian has preserved an inventory of 17 consonants very similar to Proto-Dravidian: /p t ṯ c ṭ k, m n ñ ṇ, r ẓ, l ḷ, y w *H/.
[7][8] PSD1 also innovated separate demonstrative pronouns for females with a feminine suffix *-aḷ: *avaḷ (distal) *ivaḷ (proximal), *uvaḷ (yonder).
[10][11] There are also terms for urban structures and various types of habitations including villages, towns, castles, forts, prisons (or storehouses), palaces and streets.
[11] South Dravidian I (SD1) *eḷḷu (sesame) is cognate with Akkadian ellu which suggests that the name was in use at the time of trade between the Indus Valley Civilisation (IVC) and Mesopotamia (circa 2600-1900 BC).