In the fourth aliyah, Moshe accepts the offer of the tribes of Reuvein and Gad to go to battle for the land of Israel with the rest of the Jews, after which they will return and inherit land on this side of the Jordan. So in this aliyah these tribes are given land for the families and cattle to be safeguarded while they go across the Jordan with everyone else.

(This aliyah now continues into parsha Masai.)

At the beginning of parsha Masai the Torah recounts the journeying of the Jews in the desert. Rashi says that of the 42 journeys listed here, only 20 were after the decree to wander in the desert until Aharon passed away, and that prevents anyone from saying that the Jews were made to wander continuously, without rest.