Indonesia in general is a Muslim country, but Bali is mostly populated with Hindu. Hinduism requires the dead to be burnt as the dead could rejoin the elements (ground, fire, air) for the reincarnation. But the ceremony is too expensive for the most of Balineses. That is why the dead is firstly buried for some years if his (or her) relatives don't have enough money to cremate right after death. And after 3-5 years, when some families in a village have saved money, the village organizes the centralized ceremony. The remains are exhumed and burnt in a couple of days. A lot of people from the village as well as specially engaged people participate in the multitude of rituals accompanying the ceremony.