Jin Dynasty Boundary Trench Introduction: The Jin Dynasty Boundary Trench was a huge defense project built by the Jin regime for more than 60 years to consolidate its rule and prevent enemy invasion. It runs from northeast to southwest, with a total length of about 1,000 kilometers. After excavation and research, it was found that the trench was made of mounds of earth as a long embankment, with horse faces built on the embankment. Border forts were built at intervals along the inside of the boundary trench, and pass was set up at important traffic intersections, so it is also known as "boundary trench and side fort". .