Charles Ellicott Commentary Numbers 22:4

"And Moab said unto the elders of Midian, Now will this multitude lick up all that is round about us, as the ox licketh up the grass of the field. And Balak the son of Zippor was king of Moab at that time." — Numbers 22:4 (ASV)

And Moab said to the elders of Midian— It has been thought that Balak was a Midianite, who had been imposed upon the Moabites as their king by their Amoritish conquerors. . The concluding words of the verse may be understood as denoting a recent change in the dynasty.

As the ox licks up the grass of the field. —The comparison is one which well accords with the occupation of the Moabites as a pastoral people.