Charles Ellicott Commentary Numbers 32:16

"And they came near unto him, and said, We will build sheepfolds here for our cattle, and cities for our little ones:" — Numbers 32:16 (ASV)

We will build sheepfolds ... — The sheepfolds were commonly constructed of loose stones piled up on one another.

And cities for our little ones. —The word which is rendered “build” often means to “build up” or “repair,” and it probably has that meaning in this place, as applied to the cities. (See Numbers 32:26.)