The northernmost part of Palestine consists of mountains, hills, and valleys. It is crossed by the large Jezreel Plain that runs east to west from the Mediterranean Sea to the Jordan River. South of this plain is central Palestine, which consists of rolling hills and valleys. This region became an independent country when the Israelites divided into two kingdoms, Israel and Judah, in 922 B.C.E. Israel, the northern kingdom, remained independent until it was conquered by the Assyrians in 722 B.C.E.