כָּל־הַפְּקֻדִים֙ לְמַ֣חֲנֵה דָ֔ן מְאַ֣ת אֶ֗לֶף וְשִׁבְעָ֧ה וַחֲמִשִּׁ֛ים אֶ֖לֶף וְשֵׁ֣שׁ מֵא֑וֹת לָאַחֲרֹנָ֥ה יִסְע֖וּ לְדִגְלֵיהֶֽם׃ (פ)
단의 진에 속한 계수함을 입은 군대의 총계가 십오만 칠천육백 명이라 그들은 기를 따라 후대로 진행할지니라 하시니라
Siftei Chakhamim
They traveled in the shape of a box. Like Rashi explains in Parshas Bamidbar (2:9) — the banner of Yehudah was on the east, Reuven’s on the south, Ephraim’s on the west and Don’s on the north. Therefore they had to spread out to a width of two banners and consequently [Don] had to be heavily populated. However, according to the opinion that they traveled one after the other in the shape of a beam, and deriving this from “gatherer for all the camps” — even if Don was not heavily populated, they could gather whatever was lost. You might ask: The tribes [traveling under the banner] of Yehudah were more populous than the tribes [traveling under the banner] of Don, because the tribes [traveling under the banner] of Yehudah comprised 186,400 while the tribes [traveling under the banner] of Don totaled only 157,600, as the Torah writes in Parshas Bamidbar (2:9, 31). (Gur Aryeh) answers: Yehudah traveled first, given that he was the king, and therefore the last to travel was Don who had the largest population after Yehudah.