The Rinjani caldera-forming eruption is thought to have occurred in the 13th century. Dated to late spring or summer of 1257, this 1257 Samalas eruption is now considered the likely source of high concentrations of sulfur found in widely dispersed ice core samples and may have been the most powerful volcanic blast since humans learned to write. The massive eruption may have triggered an episode of global cooling and failed harvests. Before this eruption, the Segara Anak caldera was a volcanic mountain named Samalas, which was higher than Rinjani.