| Period forwarded with battles over commerce between regions as well as battles over acquisition of cultivation land and iron for farming equipment, for development of rice-paddy cultivation. |
水田農耕発展のために農地の拡大と農具となる鉄の獲得のため、また地域間の交易をめぐる争いのために戦いが起こり時代が進行していった。 |