(Bostonglobe) - Cowboys, barbecue, and LBJ may rule Texas Hill Country, but some newcomers are making waves in this central region of the Lone Star State: winemakers. Grapes have grown on the banks of rivers here for thousands of years, yet Texas Hill Country has only recently begun to rediscover its viticulture roots. It is the nation’s second fastest-growing wine destination (behind Napa Valley), covering 15,000 square miles across 22 counties.