וַיִּלְחֲצ֧וּ הָאֱמֹרִ֛י אֶת־בְּנֵי־דָ֖ן הָהָ֑רָה כִּי־לֹ֥א נְתָנ֖וֹ לָרֶ֥דֶת לָעֵֽמֶק׃
And the Amorites forced the children of Dan into the hill-country; for they would not suffer them to come down to the valley.
Read midrashic interpretation of Judges 1:34: and classical rabbinic exegesis.