בְּיָמָיו֙ פָּשַׁ֣ע אֱד֔וֹם מִתַּ֖חַת יַד־יְהוּדָ֑ה וַיַּמְלִ֥יכוּ עֲלֵיהֶ֖ם מֶֽלֶךְ׃
In his days Edom revolted from under the hand of Judah, and made a king over themselves.
Read midrashic interpretation of II Chronicles 21:8: and classical rabbinic exegesis.