▁Middle ▁Rh ine ▁Valley . ▁ ▁L ines ▁of ▁communication ▁that ▁traverse ▁the ▁B elf ort ▁G ap ▁include ▁the ▁French ▁Route ▁nationale ▁ 8 3 ▁and ▁the ▁A 3 6 ▁autor oute , ▁the ▁railway ▁line ▁from ▁Paris ▁to ▁Bas el ▁and ▁the ▁planned ▁L GV ▁Rh in - R h ône ▁high - speed ▁railway , ▁as ▁well ▁as ▁the ▁Rh ône - R h ine ▁Canal . ▁ ▁History ▁Two ▁important ▁routes ▁crossed ▁the ▁area ▁already ▁during ▁the ▁Roman ▁era , ▁which ▁allowed ▁Julius ▁Ca esar ▁to ▁quickly ▁move ▁troops ▁which ▁were ▁used ▁to ▁defeat ▁Ari ov ist us ▁and ▁force ▁his ▁German ▁tribes ▁( prim arily ▁Sue bi ) ▁in ▁the ▁province ▁of ▁Germania ▁Super ior ▁to ▁retre at ▁across ▁the ▁Rh ine . ▁After ▁the ▁M igration ▁Period ▁and ▁the ▁Dec line ▁of ▁the ▁Roman ▁Empire ▁in ▁the ▁ 5 th ▁century , ▁German ic ▁A lem anni ▁tribes ▁settled ▁east ▁of ▁the ▁plate au , ▁while ▁the ▁Burg und ians ▁established ▁a ▁first ▁kingdom ▁west ▁of ▁it . ▁Both ▁had ▁been ▁incorpor ated ▁into ▁the ▁Kingdom ▁of ▁Francia ▁by ▁the ▁early ▁ 6 th ▁century , ▁while ▁the ▁high land ▁remained ▁the ▁lingu istic ▁border ▁between ▁German ic ▁and ▁Rom ance ▁languages . ▁ ▁Upon ▁the ▁division ▁of ▁the ▁Carol ing ian ▁Empire ▁in ▁the ▁ 9 th ▁century , ▁the ▁area ▁again ▁marked ▁the ▁border ▁between ▁East ▁Francia , ▁i . e . ▁the ▁German ▁stem ▁du chy ▁of ▁Sw ab ia , ▁in ▁the ▁east