Problem: According to many scholars, Joel was written in the 9th century b.c. However, the Greek reference in Joel 3:6 indicates that the earliest the book could have been written is the late 4th century b.c.
Solution: It is not necessary to suppose that the mention of Greeks places the composition of the book in the late 4th century b.c. The context of chapter 3 is the judgment of the nations. God promises punishment specifically upon the Phoenicians and the Philistines because they had plundered His people and sold them into slavery to the Greeks. Verse 6 states that these nations had sold His people to the Greeks: “That you may remove them far from their borders.” If Joel had been written after the expansion of the empire of Greece by Alexander the Great in the middle of the 4th century b.c., then God could not have accused the Phoenicians and the Philistines of selling the Jews to the Greeks who were “far from their borders.” The Greeks are referred to in ancient Neo-Babylonian inscriptions as early as the 7th-century b.c., and the Cretan Linear B tablets indicate the beginning of the Greek civilization and language from about 1500 b.c. So, it is not possible to use this reference to date Joel’s prophecy in the fourth century b.c.