For all the people who came out were circumcised; but all the people who were born in the wilderness by the way as they came forth out of Egypt, they had not circumcised.
Why did God wait to command the circumcision of the new generation until now rather than on the plains of Moab? Perhaps He did so because He wanted to bring the people into the land before enforcing this aspect of the Law. This is consistent with God’s dealings with humankind. He first gives and then asks (cf. Romans 12:1).