From the standpoint that the Hoken system became prevalent after the Song period, peasants under the Equal-field system were slaves and the Tien Hu system which first appeared in the Song period was regarded as a serfdom.
宋以後を封建制と見る立場からは均田制の下におかれた農民たちを奴隷とみなし、宋に入って登場した佃戸制を農奴とみなす。