In the _Zend Avesta_--the oldest sacred book of the Persians--or in such fragments of it as are left, there are sixteen countries spoken of as having been given by Ormuzd, the Good Deity, for the Aryans to live in; and these countries are described as a land of delight, which was turned, by Ahriman, the Evil Deity, into a land of death and cold; partly, it is said, by a great flood, which is described as being like Noah's flood recorded in the Book of Genesis. This land, as nearly as we can make it out, seems to have been the high, central district of Asia, to the north and west of the great chain of mountains of the Hindu Koush, which form the frontier barrier of the present country of the Afghans. It stretched, probably, from the sources of the river Oxus to the shores of the Caspian Sea; and when the Aryans moved from their home, it is thought that the easterly portion of the tribes were those who marched southwards into India and Persia, and that those who were nearest the Caspian Sea marched westwards into Europe. It is not supposed that they were all one united people, but rather a number of tribes, having a common origin--though what was this original stock is quite beyond any knowledge we have, or even beyond our powers of conjecture. But, though the Aryan peoples were divided into tribes, and were spread over a tract of country nearly as large as half Europe, we may properly describe them generally, for so far as our knowledge goes, all the tribes had the same character.