 The region was known for its wine . Since the 15th century the local inhabitants practiced <unk> and the wine producers formed St. Paul <unk> ' Guild in <unk> , the oldest such guild in the German @-@ speaking world . <unk> vineyards extended up the sides of the <unk> River until it became a mountain stream and terrain was unsuitable for cultivation . The <unk> plain supported both <unk> and agriculture . As the terrain became <unk> , the vines grew in terraces built from the dark <unk> , primordial rock . From <unk> to <unk> the river makes its wide curve ; the mountains and the steeply terraced slopes prevent clear line @-@ of @-@ sight between the two towns . 
