▁it ▁requires ▁an ▁un real ist ically ▁early ▁date . ▁Most ▁estimates ▁date ▁Pro to - Ind o - Europe an ▁between ▁ 4 5 0 0 ▁and ▁ 2 5 0 0 ▁BC , ▁with ▁the ▁most ▁probable ▁date ▁around ▁ 3 7 0 0 ▁BC . ▁It ▁is ▁unlikely ▁that ▁late ▁P IE , ▁even ▁after ▁the ▁separation ▁of ▁the ▁An atol ian ▁branch , ▁post dates ▁ 2 5 0 0 ▁BC , ▁as ▁Pro to - Ind o - I ran ian ▁is ▁usually ▁dated ▁to ▁just ▁before ▁ 2 0 0 0 ▁BC . ▁On ▁the ▁other ▁hand , ▁it ▁is ▁not ▁very ▁likely ▁that ▁early ▁P IE ▁pred ates ▁ 4 5 0 0 ▁BC , ▁as ▁the ▁re construct ed ▁voc ab ul ary ▁strongly ▁suggests ▁a ▁culture ▁of ▁the ▁terminal ▁phase ▁of ▁the ▁Ne ol ith ic ▁border ing ▁on ▁the ▁early ▁Bron ze ▁Age . ▁ ▁L ingu istics ▁Many ▁Ind o - Europe an ▁languages ▁have ▁cogn ate ▁words ▁meaning ▁ax le : ▁Latin ▁axis , ▁Lith uan ian ▁a š is , ▁Russian ▁os ' ▁, ▁and ▁S ansk rit ▁á k ṣ a . ▁( In ▁some , ▁a ▁similar ▁root ▁is ▁used ▁for ▁the ▁word ▁ar mp it : ▁e ax l ▁in ▁Old ▁English , ▁ax illa ▁in ▁Latin , ▁and ▁k ak sa ▁in ▁S ansk rit .) ▁All ▁of ▁them ▁are ▁linked ▁to ▁the ▁P IE ▁root ▁ak ' s -. ▁The ▁re construct ed ▁P IE