傳統視域里民族政策只是反映政府對民族地區由上而下的管理，較少關注民族需求及上下交互式的政策演變。宋朝政府在西南地區實施的羈縻政策發生了變化，主要緣于溪峒與政府之間物質價值認同的遷移。食鹽作為溪峒民族的生活必需品，曾一度成為溪峒與政府之間價值認同的媒介，一方面，緣于溪峒民族對食鹽的需求程度高漲;另一方面，宋朝政府抓住食鹽的貨幣職能謀求區域社會的穩定。從北宋前期"以鹽易米"到南宋中后期的"以鹽轉易多物"，食鹽交換成為宋朝政府在西南民族地區羈縻政策的重要手段。這種與宋代茶鹽專賣制度背道而馳的食鹽交換手段，不僅實現了政府對民族地區的有效控制，也反映出國家民族政策的制定或推行必須先期平衡中央與地方的雙向需求。

In the traditional understanding,the ethnic policy is reflected in the government’ s top-down management in minority areas; little attentions are paid to the needs of the minorities and evolution of the interactive policy. The change of the bridle policy of the Song central government implemented in the Southwest areas resulted mainly from the change of value system over material goods between the mountainous areas and the government. As a kind of living necessity in the life of minorities in such regions,salt was once served as a medium to achieve mutual recognition between the mountainous areas and the government.On the one hand,the need for salt of minorities in these areas increased,and on the other hand,the Song government took advantage of the cash function of salt to stabilize the regional society. The exchange of salt became an important solution of the bridle policy of the Song government implemented in the Southwest minority areas from the early North Song dynasty when the salt was used to exchange rice to the mid- later period of the South Song dynasty when the salt was used to exchange more items. Such means as salt exchange which was contradictory to the monopoly system of tea and salt of the Song government not only helped the government to achieve effective control over the minority areas,but they also reflected that the making or implementation of ethnic policy must balance the mutual needs between the central and local governments in advance.