Which raiders formed three bands and carried off Job's camels?

Answer: The Chaldeans

Job 1:17: "The Chaldeans formed three bands, raided the camels, and took them away." The Sabeans had taken the oxen and donkeys.

“While he was still speaking, another messenger came and reported: “The Chaldeans formed three bands, raided the camels, and took them away. They put the servants to the sword, and I alone have escaped to tell you!””— Job 1:17 (BSB)