The ethnonym 'Iranians' comes from the historical name 'Iran', derived from the ancient Iranian Aryan (land), (land) of the Aryans. Iranian or Aryan peoples are a group of peoples of common origin, speaking Iranian-speaking Aryan branch of the Indo-European family of languages, formed in the steppes of the Southern Urals - Black Sea Coast. The oldest population of Iran, in its western part, from the 4th millennium B.C. were Elamites, Kassites and their kindred tribes; part of them may be Hurrians. The languages of these tribes were not part of either the Semitic or Indo-European family of languages. The tribes that spoke Iranian languages appeared in Iran at the beginning of the 1st millennium B.C.. Gradually, it is planned to establish agricultural areas in a number of areas of Central Asia: in the Areya - along Tejen (Gerirud), Margiana - along Murghab, Bactria - in the upper reaches of the Amu Darya, Sogdiana - in the Kashka-Darya and Zaravshan, Khorezm (Khorasmiya) - along the lower reaches of the Amu Darya and near the Sarykamysh Basin. Both nomadic and sedentary tribes spoke the languages of the Iranian group of the Indo-European family. Many hydronyms (names of rivers) have a distinct character of the Aryan tribes - Daria (from 'Arya').