When the judges ruled - We know not under what judge this happened; some say under Ehud, others under Shamgar. See the preface.
There was a famine - Probably occasioned by the depredations of the Philistines, Ammonites, etc., carrying off the corn as soon as it was ripe, or destroying it on the field.
The Targum says: "God has decreed ten grievous famines to take place in the world, to punish the inhabitants of the earth, before the coming of Messiah the king. The first in the days of Adam; the second in the days of Lamech; the third in the days of Abraham; the fourth in the days of Isaac; the fifth in the days of Jacob; the sixth in the days of Boaz, who is called Abstan, (Ibzan), the just, of Beth-lehem-judah; the seventh in the days of David, king of Israel; the eighth in the days of Elijah the prophet; the ninth in the days of Elisha, in Samaria; the tenth is yet to come, and it is not a famine of bread or of water but of hearing the word of prophecy from the mouth of the Lord; and even now this famine is grievous in the land of Israel."
In the days when the Judges ruled - “Judged.” This note of time, like that in Rth 4:7 ; Judges 18:1; Judges 17:6, indicates that this Book was written after the rule of the judges had ceased. The genealogy Rth 4:17-22 points to the time of David as the earliest when the Book of Ruth could have been written.
A famine - Caused probably by one of the hostile invasions recorded in the Book of Judges. Most of the Jewish commentators, from the mention of Bethlehem, and the resemblance of the names Boaz and Ibzan, refer this history to the judge Ibzan Judges 12:8, but without probability.
The country of Moab - Here, and in Rth 1:2 , Rth 1:22 ; Rth 4:3 , literally, “the field” or “fields.” As the same word is elsewhere used of the territory of Moab, of the Amalekites, of Edom, and of the Philistines, it would seem to be a term pointedly used with reference to a foreign country, not the country of the speaker, or writer; and to have been specially applied to Moab.