淮南地區在唐代是主要的食鹽產地之一，唐代淮南地區擁有揚州海陵監及楚州鹽城監等二大鹽監，其中尤以海陵監產量最大，與鹽城監合計年產量達百萬石之譜。淮南地區由於製鹽業發達且位於運河的要道上，為了有效管理鹽務和漕運，唐廷先後在淮南地區設置了七個巡院，其中以揚子留後最為重要，揚子留後主要負責江淮地區的漕運和鹽務，唐末甚至往嶺南地區的海運也是由其管理，其重要性可見一斑。因此本文除探討淮南地區的食鹽生產及銷售外，同時也對淮南地區巡院的性質、職能和組織等方面進行深入的探究。
Huainan area was one of the main places of salt production in Tang Dynasty, including two major districts: Yangzhou Hailing and Chuzhou Yancheng. Hailing district had the highest productivity, and its output adding Yancheng's would reached million hectoliters annually. In order to manage the developed salt industry and canal transportation in Huainan area, the government set up six Xunyuans, the special agencies, within this area successively. Yangtze Liuhou was the most important one of all, responsible for managing the salt industry and canal transportation in Jianghuai area, and its territory was even expended to the ocean shipping in Lingnan area at the end of Tang Dynasty, which indicated its importance then. Therefore, besides the salt production and market of Huainan area, the study will also research Xunyuan's feature, role and responsibility, and its organization thoroughly.
