Upon acquisition of his first territories in the First Division, Brooke came into possession of a large quantity of antimony from mines around the area. At the time of his arrival, a land tenure system known as the Native Customary Rights (NCR) had been practised by the indigenous communities. Brooke's first priority was to abolish headhunting among the indigenous communities of the interior. The kingdom's authorities conducted repeated raids on Sea Dayak villages and, facing a major rebellion, ultimately forced them to practice horticulture and abandon headhunting. Land Dayaks had also been involved in headhunting but more readily abandoned the practice and became loyal followers of Brooke. Most Malay coastal villages were also raided as part of the kingdom's policy to combat piracy and slavery. Despite success in these endeavours, stagnant economic conditions persisted and the kingdom amassed huge debts.