Who were the Eirev Rav?
Rashi, Targum Onkelos and Targum Yonasan: The Eirev Rav were a mixture of Nochrim from various countries, who converted and joined the ranks of Bnei Yisrael.
How many people did the Eirev Rav comprise?
Targum Yonasan: They comprised two million, four hundred thousand people. 1
Four times as many as Yisrael themselves. See also Perush Yonasan.
Why does the Torah write "Alah Itam," and not 'Alah Imam'?
Oznayim la'Torah: As the Vilna Gaon explains, 'Imam' implies 'with the same intention;' whereas 'Itam' means 'independently.' The Erev Rav joined Yisrael to escape the cruel tyrant Pharaoh, not in search of spiritual perfection, like Yisrael, who followed Moshe into the desert in order to receive the Torah. 1
Oznayim la'Torah: Which explains why they turned out to be a constant thorn in Yisrael's side; they were the ones to make the Egel ha'Zahav. See Oznayim la'Torah.
What is the significance of the sheep and cattle mentioned in the Pasuk?
Rashi (to Bamidbar 11:4): It refers to the sheep and cattle that Yisrael took with them when they left Egypt.
Rashbam: It refers to the sheep and cattle that belonged to the Eirev Rav. 1
In that case, the Torah says nothing about the sheep and cattle of Yisrael?
QUESTIONS ON RASHI
Rashi writes: "Eirev Rav - Mixed nations of converts." The Midrash writes that Moshe sent Yisro home (18:27) prior to the Giving of the Torah, for only the people who had been enslaved in Egypt deserved to rejoice upon receiving the Torah. If so, why were the Eirev Rav permitted to remain?
Maharal (Derush Al Ha'Torah, intro p. 6, printed after Be'er ha'Golah): The Eirev Rav mixed with Bnei Yisrael and became subsumed within them; such that they could remain with them for Matan Torah. The name "Yisro," on the other hand, expresses the meaning "extra," or "add-on." [Yisro retained his own identity;] the Bnei Yisrael needed him, such that he could not become negated to them. 1
See Maharal further as to why having been enslaved was a prerequisite for receiving the Torah.
