The same tribal leaders who helped with the registration in chapter 1 also appear in 7:2–3. The non-Levitical tribes gave the Gershonites and Merarites wagons and oxen to move the heavy parts of the tabernacle and other items (see chapter 4).
These vehicles and animals were the first offerings from the Hebrew tribes (7:2). The tribal leaders also presented these practical gifts along with the more elaborate offerings they dedicated (7:10, 12–83).