Dan was born on the 9th of Elul, and he lived 125 years.
Dan is the first son of Yaakov and Bilhah, the handmaiden of Rachel, and the fifth son of Yaakov overall.
He was the first son born under the auspices, so to speak, of Rachel, after she said in desperation to Yaakov, “…Give me children, for if not, I am dead.” (Bereshit 30:1) And Yaakov responded, “…Am I in the place of G-d, Who has withheld from you the fruit of the womb? Then Rachel said ‘Here is my handmaiden, Bilhah, consort with her, that she may have children upon my knees and I too may be built up through her.” (Bereshit 30:2-3)
Bilhah gave birth to a son, and “Then Rachel said, ‘G-d has judged me and He has also heard my voice and given me a son.’ She therefore called him’Dan.’ ” (Bereshit 30:6) (“Dan” is from the same “shoresh,” or linguistic root, as the Hebrew word “Din,” meaning Judgment)
When the Torah lists the “seventy souls” who came down to Egypt with Yaakov (Bereshit 46:8-27), Dan is described as having one son, “Chushim.” “Targum Yonatan” on verse Bereshit 46:23 writes that is also a description of Dan’s descendants; “quick and sharp and very prolific,” in order to account for their tremendous population, second only to the Tribe of Yehudah.
In Birchot Yaakov, the Blessings of Yaakov (Bereshit 49:1-28), Dan’s father prophesies concerning Shimshon, one of the “Shophtim,” or Judges, who would almost single-handedly lead Israel against their enemy throughout the “Tanach,” the Bible, the “P’lishtim,” or Philistines. Yaakov compares Shimshon to a snake who bites the heels of a horse, causing the rider to fall, referring to Shimshon’s final victory when, blind and in chains, he asks HaShem to restore his super-human strength one last time, and he pushes apart the columns of the Philistine Temple, killing more than three thousand people, including himself, as he shouts, “Let me die together with the P’lishtim.” (Shophtim, Chapter 16)
The Tribe of Dan, under the leadership in the Wilderness of Achiezer ben Amishaddai, was the central tribe of the fourth and final group or “encampment” of tribes, that acted as the “rear guard” of the Twelve Tribes of Israel.” They would collect individuals who had become detached from their tribes and fight off enemy attacks that would tend to attack from the rear.
In “Birchot Moshe,” the “Blessings of Moshe,” Moshe Rabbeinu prophetically compared the Tribe of Dan as a border guard in the “Eretz Yisrael,” the Land of Israel, to a “lion cub.” (Devarim 33:22)