If from these indications about the customs of Brahmavarta and the Brahmans of Brahmarshideça we can determine with tolerable certainty the region in which the book of the law has grown up, it follows from the introduction in which the holy Bhrigu recites the law as "Manu had revealed it to him at his prayer," and from the close where we are again told that this is "the law announced by Bhrigu,"[225] that the collection of Brahmanic rules contained in this book have been preserved in the form and revision received in the school derived from Bhrigu, and connected with the old minstrel race of the Bhrigus.[226] It is more difficult to find the date at which the germ of this collection of law may have been brought to completion. Even if we set aside the introduction and the close which are in no connection with the body of the work, the book is still wanting in unity: it contains longer and shorter rules on the same subject, is sometimes milder, sometimes more severe; a fact in favour of the gradual origin of the book, which indeed, as has been observed, is necessitated by the nature of the case. The Indians possess a series of books of law, which, like that called after Manu, bear the name of a saint or seer of antiquity, or of a god. One is named after Gautama, another after Vasishtha, a third after Apastamba, a fourth after Yajnavalkya; others after Bandhayana and Vishnu. According to the tradition of the Indians the law of Manu is the oldest and most honourable, and this statement is confirmed by a comparison of the contents and system of the rules contained in it with those of the other books.[227] Not to mention the fact that a considerable number of the rules in the book of Manu are repeated verbally in the other collections, the legal doctrine of the Indians is seen even in the older of these collections, in the book of Vishnu, which belongs to the Brahman school of the Kathakas, in that of Gautama, and finally in that of Yajnavalkya, which with the book of Gautama is nearest in point of date to the book of Manu--in a far more developed state, and with much more straw-splitting refinement. The book which is named after Yajnavalkya of the race of Vajasani belongs to the eastern regions of the Ganges, the kingdom of Mithila. It is based on a doctrine which, unknown to Manu's law, came into existence in the fourth century B.C.; the system of mixed castes and trade law is far more developed in it than in Manu. We shall see below that this doctrine cannot be placed much further back than the year 300 B.C.,[228] and it is assumed that the laws of Yajnavalkya in their present form may date from the third century of our era. If Manu's law is older than Yajnavalkya's, and the latter rests on a doctrine, the rise of which we can fix about the year 300 B.C., while Manu's doctrine is older, there are other indications to be gathered from Manu's work which enable us to fix the date more clearly.