These were counted from the Gershonite clans who served at the Tent of Meeting, whom Moses and Aaron counted at the LORD’s command.
KJV
These [are] they that were numbered of the families of the sons of Gershon, of all that might do service in the tabernacle of the congregation, whom Moses and Aaron did number according to the commandment of the LORD.
ASV
These are they that were numbered of the families of the sons of Gershon, all that did serve in the tent of meeting, whom Moses and Aaron numbered according to the commandment of Jehovah.