Albert Barnes Commentary 2 Kings 13:20

"And Elisha died, and they buried him. Now the bands of the Moabites invaded the land at the coming in of the year." — 2 Kings 13:20 (ASV)

The bands of the Moabites invaded the land - The Moabites had been increasing in strength ever since their revolt from Ahaziah (2 Kings 1:1). The defeat they suffered at the hands of Jehoram and Jehoshaphat (2 Kings 3:24) did not lead to their subjugation.

They spread into the country north of the Arnon (Isaiah 16:2) and from there proceeded to make plundering expeditions into Samaria each spring. This was the natural season for such raids, since at that time in Palestine the crops were beginning to ripen.