John Gill Commentary Joshua 22:21

"Then the children of Reuben and the children of Gad and the half-tribe of Manasseh answered, and spake unto the heads of the thousands of Israel," — Joshua 22:21 (ASV)

Then the children of Reuben, and the children of Gad, and the
half tribe of Manasseh, answered
By some person whom they appointed to deliver the answer in their name:

and said unto the heads of the thousands of Israel ;
who were over those that were rulers of the thousands of Israel, persons of greater authority than they, being princes of the respective tribes to which they belonged.