In research based upon rice plant DNA in recent years, it is assumed that the introduction of temperate Japonica cultivation by wet-rice agriculture was most likely introduced by the southern route since the variations in rice plant DNA were fewer on the Korean peninsula.
温帯ジャポニカによる水稲農耕の始まりも近年の稲DNAに基づく研究では、DNAの多様性が朝鮮半島の方が少ないことから南方経由の可能性が高いとされている。