Deuteronomy 4:49 Midrash

וְכָל־הָ֨עֲרָבָ֜ה עֵ֤בֶר הַיַּרְדֵּן֙ מִזְרָ֔חָה וְעַ֖ד יָ֣ם הָעֲרָבָ֑ה תַּ֖חַת אַשְׁדֹּ֥ת הַפִּסְגָּֽה׃ (פ)

and all the Arabah beyond the Jordan eastward, even unto the sea of the Arabah, under the slopes of Pisgah.

Read midrashic interpretation of Deuteronomy 4:49: and classical rabbinic exegesis.