sentences:  Later, about 1819, Koh helped Sultan Jauhar al-Alam put down a rebellion by Acehnese territorial chiefs.In the 1820s, as Aceh produced over half the world's supply of pepper, a new leader, Tuanku Ibrahim, was able to restore some authority to the Sultanate and gain control over the "pepper rajas" who were nominal vassals of the Sultan by playing them off against each other.He rose to power during the Sultanate of his brother, Muhammad Syah, and was able to dominate the reign of his successor Sulaiman Syah (r. 1838–1857), before taking the Sultanate himself, under the title Sultan Ali Alauddin Mansur Syah (1857–1870).