In Joel 3, to which people did Tyre and Sidon sell the people of Judah?

Answer: The Greeks

Tyre, Sidon and Philistia sold the people of Judah to the Greeks. God said Judah would in turn sell their children to the Sabeans.

“You sold the people of Judah and Jerusalem to the Greeks, to send them far from their homeland.”— Joel 3:6 (BSB)