As a proto-language, the Proto-Dravidian language is not itself attested in the historical record. Its modern conception is based solely on reconstruction. It was suggested in the 1980s that the language was spoken in the 4th millennium BCE, and started disintegrating into various branches around 3rd millennium BCE. According to Krishnamurti, Proto-Dravidian may have been spoken in the Indus civilization, suggesting a "tentative date of Proto-Dravidian around the early part of the third millennium." Krishnamurti further states that South Dravidian I (including pre-Tamil) and South Dravidian II (including Pre-Telugu) split around the eleventh century BCE, with the other major branches splitting off at around the same time. Kolipakam et al. (2018) estimate the Dravidian language family to be approximately 4,500 years old.