The drainage from the Yamuna may have been lost from the Ghaggar-Hakra well before the beginnings of Indus civilisation. Ajit Singh et al. (2017) show that the paleochannel of the Ghaggar-Hakra is a former course of the Sutlej, which diverted to its present course between 15,000 and 8,000 years ago, well before the development of the Harappan Civilisation. Ajit Singh et al. conclude that the urban populations settled not along a perennial river, but a monsoon-fed seasonal river that was not subject to devastating floods. Rajesh Kocchar further notes that, even if the Sutlej and the Yamuna had drained into the Ghaggar during Rig Vedic, it still would not fit the Rig Vedic descriptions because "the snow-fed Satluj and Yamuna would strengthen lower Ghaggar. Upper Ghaggar would still be as puny as it is today." An alternative suggestion for the identity of the early Rigvedic Sarasvati River is the Helmand River and its tributary Arghandab in the Arachosia region in Afghanistan, separated from the watershed of the Indus by the Sanglakh Range. The Helmand historically besides Avestan "Haetumant" bore the name "Haraxvaiti", which is the Avestan form cognate to Sanskrit "Sarasvati". The Avesta extols the Helmand in similar terms to those used in the Rigveda with respect to the Sarasvati: "the bountiful, glorious Haetumant swelling its white waves rolling down its copious flood". However unlike the Rigvedic Sarasvati, Helmand river never attained the status of a deity despite the praises in the Avesta. The identification of the "Sarasvati" river with the "Helmand" river was first proposed by E. Thomas in 1886, followed by Alfred Hillebrandt a couple of years thereafter. However, in the same year, Geologist R.D. Oldham, refuted this Afghan Sarasvatī thesis. Indologist A.B. Keith (1879-1944) also didn't subscribe to this theory and stated that there is no conclusive evidence to identify the Sarasvati with the Helmand river. According to Konrad Klaus, the geographic situation of the Sarasvati and the Helmand rivers are similar. Both flow into a terminal lakes: the Helmand into a swamp in the Iranian plateau (the extended wetland and lake system of Hamun-i-Helmand).