By the late sixteenth century, however, conflicts over land between indigenous Jurchens and Korean settlers were increasingly frequent. The Jurchen chieftain Nitanggae rebelled in 1583, severely undermining the Korean state's control of the area. The crisis was exacerbated by the large-scale Japanese invasion in 1592 during which Katō Kiyomasa conquered large parts of Hamgyŏng, leading to a breakdown of the Korean administration and major conflicts between Jurchens and Koreans.