Saul had begun his reign by rescuing Jabesh in Gilead from the Ammonite king Nahash, who had threatened to treat its inhabitants with innate Semitic barbarity.

When civil war broke out in Israel, Nahash naturally befriended David, and the alliance continued after David's accession to the throne.

Common interests brought them together.

Esh-Baal, the successor of Saul in Gilead, was the enemy of both: his frontier adjoined that of Ammon, while between him and the King of Judah there was perpetual war.

David had strengthened himself by marrying the daughter of the king of the Aramaic district of Geshur, which bounded Gilead on the north, and Ammonites and Aramaeans were in close alliance with each other.
As long as Nahash lived, there was peace between him and David.