Where did the demons go when Jesus drove them out of the men?

Answer: Into a herd of pigs

Jesus said, "Go!" and the demons went into the pigs; the whole herd rushed down the steep bank into the sea and died.

“So the demons begged Jesus, “If You drive us out, send us into the herd of pigs.” “Go!” He told them. So they came out and went into the pigs, and the whole herd rushed down the steep bank into the sea and died in the waters.”— Matthew 8:31-32 (BSB)