The idea of recording one’s family history and understanding genealogical descent is an integral part of the Torah, which includes 477 genealogical records. The Prophets and other books of the Bible include 2,756 genealogical records. And Divrei Hayamim (Chronicles) is almost entirely concerned with genealogy.
Yikhus (lineage) has always been an integral part of Judaism. In the opening chapters of the Bible, in the weekly Torah portion, the concept of recording the history of mankind appears with the use of the term Sefer Toldot Adam (Book of the history of man), Bereishit (Genesis) 5:1.
The Midrash (Midrash Rabba, Parasha 24) explains this term to indicate that Adam, the first man, was given a preview of all the generations that were destined to descend from him:
God revealed to Adam each generation with its scholars, each generation and its wise men, each generation and its writers, each generation and its leaders. Adam was the only one who saw the yikhus which descended from him, until the end of all generations. (Yalkut Shimoni)
The Midrash asserts that the Messiah will arrive only when all those generations that were predestined to live have in fact been born.
The course of the Biblical narrative revolves around the sequence of the generations, from the early generations descended from Adam, through the division of the nations descended from Noakh, and down to the Jewish Patriarchs: Avraham, Yitzhak and Yaakov (Abraham, Isaac, Jacob). Each major figure is introduced in the Bible first by a narration of his descent, connecting him with all the previous generations. Thus, the great Jewish teacher Moshe (Moses) is introduced through his father’s descent from the tribe of Levi. From the time of the descent of the Children of Israel to Egypt and following their liberation from Egyptian bondage, their genealogy is noted at the very beginning of the book of Shmot (Exodus). Time and time again throughout the Bible, lengthy genealogical lists are recorded.
For the Jews returning from the Babylonian Exile, it was particularly important that they retained knowledge of their descent. This knowledge conferred upon them their status in society, which was often based on their relationships with prominent families, in particular, the ruling House of David. Those who had assimilated with their non-Jewish neighbors in Babylon found that their lineage was held in suspicion, particularly if they belonged to the priesthood. Such problems are portrayed in detail in the book of Ezra:
They sought their genealogical records, but they were no longer available, and so they were banished from the priesthood. Those immigrants could not state which was their father’s house or whether they were of the seed of Yisrael. (Ezra 2:62)