Thereafter, Yoshikuni and his eldest child, Yoshishige NITTA developed Nitta County, Kozuke Province (Ota City, Gunma Prefecture, former Nitta-machi, Nitta-gun, etc.) on the other side of the Watarase-gawa River which had been devastated by the eruption of Mt. Asama, and donated the developed land to FUJIWARA no Tadamasa in the Taira family side in 1157, which established Nitta no sho estate.
その後、義国と長子の新田義重は渡良瀬川対岸の浅間山噴火で荒廃していた上野国新田郡（群馬県太田市、旧新田郡新田町など）を開発し、保元2年（1157年）平家方の藤原忠雅に開発地を寄進し、新田荘が立荘された。