The Emergence of Earthen Fortifications and the Formation of Construction Techniques

This paper examines the emergence of ancient earthen fortifications and the construction techniques that laid their foundations, under the premise that the appearance of ancient fortresses coincides with the formation of fortress construction techniques. Ancient fortresses first appeared as defensive structures characterized by walls and later evolved into significant political and administrative symbols for states. Among these, earthen fortifications, as suggested by the character ‘城’, represent an early form of such defensive walls, indicating a long-standing history. Literature records show that these fortifications existed prior to the Three Kingdoms period. Archaeological investigations of Bronze Age ditch enclosures indicate that the soil excavated from creating these enclosures was used to build earthen walls, which gradually developed into the defensive settlements known as earthen fortifications. In terms of the formation of construction techniques, the ability to build earthen fortifications likely did not emerge suddenly during the Three Kingdoms period. Constructing walls with soil requires appropriate techniques, specifically the technique of compaction, which means ‘to firmly pack soil.’ This compaction technique stemmed from accumulated civil engineering experiences since the Neolithic period and laid the groundwork for building earthen fortifications and other earthen structures. Recent findings of compaction marks in domestic earthen fortifications reveal that this technology had matured by the Three Kingdoms period. Therefore, it can be concluded that the practice of compacting soil began as early as the Neolithic period, evolving through the earthen walls of Bronze Age ditch enclosures into the form of fortifications. However, there remains a gap between the earthen walls of the Bronze Age and the construction of Three Kingdoms period fortifications. Future archaeological research is expected to further elucidate the emergence of these fortifications and the early techniques used in their construction.