The children of Israel did eat manna forty years. Kalisch observes that the actual time was not forty full years, but about one month short of that period, since the manna began after the fifteenth day of the second month of the first year (Exodus 16:1) and terminated just after Passover of the forty-first year (Joshua 5:10-12).
It may be added that Mesas cannot have written the present passage later than about the eleventh month of the fortieth year (Deuteronomy 1:3; Deuteronomy 34:10; Joshua 4:19); when the manna had continued thirty-nine years and nine months.
Until they came to a land inhabited. Kalisch translates "the land of their habitation," or "which they were to inhabit," remarking that they had reached inhabited countries, e.g; those of Sihon and Og, much earlier.
But the words will not bear this rendering. What the writer intends to note is, that the manna continued all the time they were in the wilderness, until they reached inhabited territory, and then further (in the next clause), that it lasted after that, until they came to the borders of Canaan.
He does not say that it even then left off. He writes exactly as Moses might be expected to have written towards the close of his life. A later writer would, as Canon Cook observes, have been more specific.