Indo-European copula copula (with corresponding voiceless and voiced fricatives) existed side by side in Germanic, and the involvement of a separate root "" is unnecessary. The root "*(s)teh-" meant "to stand". From this root comes the present stem of the so-called "substantive verb" in Irish and Scottish Gaelic, "tá" and "tha" respectively. On the absence of the initial s- in Celtic, see Indo-European s-mobile. In Latin, "stō, stare" retained the meaning "to stand", until local forms of Vulgar Latin began to use it as a copula in certain circumstances. Today, this survives in that several Romance languages (Galician-Portuguese, Spanish, Catalan) use it
Indo-European migrations are scattered as far south as the Koppet Dag (Turkmenistan), the Pamir (Tajikistan) and the Tian Shan (Kyrgyzstan). The northern boundary vaguely corresponds to the beginning of the Taiga. In the Volga basin, interaction with the Srubna culture was the most intense and prolonged, and Federovo style pottery is found as far west as Volgograd. Most researchers associate the Andronovo horizon with early Indo-Iranian languages, though it may have overlapped the early Uralic-speaking area at its northern fringe. The Bactria-Margiana Culture, also called "Bactria-Margiana Archaeological Complex" (BMAC), was a non-Indo-European culture which influenced the Indo-European groups of the second stage