The list in Numbers 1:5–16 merely served the purpose of recording the identity of Moses’ personal assistants from each tribe. This particular list (Numbers 1:20–44) follows a similar pattern, but already groups the tribes in accordance with their encampment. Therefore, Gad is grouped here with Ruben and Simeon (which will comprise the southern camp, see Numbers 2:3–31).
20 The people of Reuben, Israel’s firstborn, their generations, by their clans, by their fathers’ houses, according to the number of names, head by head, every male from twenty years old and upward, all who were able to go to war: