Restoration map of the state bridge in the Ming Dynasty. The relief murals of the Northern Song Dynasty on the stone wall of the Zhouqiao Bridge from the Kaifeng Institute of Cultural Relics and Archaeology. The Tuzhou Bridge of Kaifeng Cultural Relics and Archaeology Research Institute is a landmark building in the center of Tokyo City in the Northern Song Dynasty. The determination of the location of the state bridge and Bian River provides a reliable space-time coordinate for the city of Tokyo, and is of great significance to the study of the urban layout structure. The Northern Song Dynasty is an important period for the maturity of stone carving art in China. The stone wall of Zhouqiao represents the level of relief art in the Song Dynasty, and is also the largest stone carving mural of the Northern Song Dynasty found in China at present. The excavation of the Zhouqiao site shows the evolution of the construction, use, and development of the Kaifeng section of the Bianhe River from the Tang and Song Dynasties to the Qing Dynasty, filling the gap in the heritage of the Tokyo section of the Grand Canal of China. In Tokyo, the capital of the Northern Song Dynasty (now Kaifeng, Henan Province), the state bridge is a landmark building in the center of the city and the hub of the Imperial Street. The Royal Street is the central axis connecting the north and south of Tokyo City. Because the east-west Bian River cuts off the Royal Street, the state bridge on the Bian River connects the Royal Street and becomes a part of the Royal Street. There is a description of the "state bridge" in "The Dream of Tokyo": "The state bridge, which is exactly named Tianhan Bridge, is facing the Great Inner Royal Street... There are stone walls on both sides of the bridge, carved with the shape of sea horses, water animals and flying clouds, under the bridge are densely lined with stone columns, covered with cars to drive the road." According to the notes of the Song people, the envoys of the Southern Song Dynasty, Fan Chengda, Lou Key, Yang Huan, and others passed by the former capital Bianjing, and have seen or passed the state bridge. Fan Chengda also left the famous poem "State Bridge": "The south and north of the State Bridge are the streets of heaven, and my father is waiting to drive back in his old age. He asked the messenger in tears, when will the six armies really come?" This shows that the State Bridge was still in normal use at that time. The excavation of Zhouqiao is one of the key points of the archaeological site of Tokyo City in the Northern Song Dynasty, which can be said to provide reliable space-time coordinates for the city. It is difficult to find traces. The overlapping of ancient and modern cities increases the difficulty of archaeology. The overlapping of urban relics of past dynasties is a prominent archaeological feature of today's Kaifeng City. During the Northern Song Dynasty, the Grand Canal ran through the eastern capital and the Bian River was very prosperous on both sides. During the Ming and Qing dynasties, the Yellow River burst and flooded many times near Kaifeng, resulting in the remains of the Song Dynasty buried 7 to 13 meters below the current Kaifeng city. In addition, the high groundwater level made the ruins of Tokyo City difficult to study and trace. The archaeologists of Kaifeng for several generations have never stopped exploring the ruins of Tokyo City, and have fully learned from the rich experience accumulated in the archaeology of "ancient and modern overlapping city sites" in China. With the rapid development of urban infrastructure, the underground water level in Kaifeng has dropped significantly, which provides an opportunity for archaeological work. Since 2012, the archaeological department has successively excavated the Shuntianmen Site in Tokyo of the Northern Song Dynasty, the Dianyi Site of the Ming Dynasty's King's Mansion, and the Yongning Prefecture Palace Site of the Ming Dynasty. In October 2018, with the approval of the State Administration of Cultural Relics, Henan Provincial Institute of Cultural Relics and Archaeology and Kaifeng Municipal Institute of Cultural Relics and Archaeology (now Kaifeng Municipal Institute of Cultural Relics and Archaeology) launched the excavation of the Zhouqiao and Bianhe sites. The archaeological team first excavated the Bianhe River channel on the east side of the Zhouqiao, sorted out the depth of the strata in different periods, cleared the width of the Bianhe River, the bank accumulation and the channel siltation form from the Song Dynasty to the Ming and Qing Dynasties, and accumulated data for the excavation of the Zhouqiao site. In March 2020, the excavation of the Zhouqiao site was officially started. The site is located at the foot of today's Zhongshan Road, which is one of the old urban areas of Kaifeng