Mount Merapi, Gunung Merapi (literally Fire Mountain in Indonesian/Javanese), is an active stratovolcano located on the border between Central Java and Yogyakarta, Indonesia. It is the most active volcano in Indonesia and has erupted regularly since 1548. It is located approximately 28 kilometres (17 mi) north of Yogyakarta city, and thousands of people live on the flanks of the volcano, with villages as high as 1,700 metres (5,600 ft) above sea level.

The name Merapi could be loosely translated as 'Mountain of Fire'. The etymology of the name came from Meru-Api; from the Javanese combined words; Meru means "mountain" refer to mythical mountain of Gods in Hinduism, and api means "fire". Smoke can be seen emerging from the mountaintop at least 300 days a year, and several eruptions have caused fatalities. Hot gas from a large explosion killed 27 people on 22 November in 1994, mostly in the town of Muntilan, west of the volcano. Another large eruption occurred in 2006, shortly before the Yogyakarta earthquake. In light of the hazards that Merapi poses to populated areas, it has been designated as one of the Decade Volcanoes.

Mas Penewu Surakso Hargo, better known as Mbah Maridjan ("Grandfather Maridjan") (5 February 1927? – 26 October 2010) was the spiritual guardian or "gatekeeper" of the Indonesian volcano Mount Merapi. His birthplace was in the mountainside hamlet (Indonesian language-dukuh) of Kinahrejo, Umbulharjo Village, Cangkringan District, of the Sleman Regency, on the island of Java in Indonesia.

He was killed at the age of 83 by a pyroclastic flow that destroyed his home in the village of Kinahrejo during the 2010 eruption of Mount Merapi.

Maridjan was the son of the previous guardian, Mbah Hargo. He was appointed to the palace staff of the Sultan of Yogyakarta, Sri Sultan Hamengkubuwono IX, in 1970 and was given the title of Raden Ngabehi Surokso Hargo. He replaced his father as guardian in 1982.

The spiritual guardian of the mountain is believed by local people to have the power to speak to the spirits of Mount Merapi, which the Javanese consider to be a sacred mountain. Maridjan led ceremonies to appease the spirits of the volcano by presenting them with offerings of rice and flowers in and around the crater. One of his most important duties was the performance of the annual Labuhan sacrificial ceremony dedicated to the spirits of Mount Merapi. A procession from the royal palace on Yogjakarta led by the guardian sacrifices to the volcano spirits a set of ritual offerings including textiles, perfume, incense, money and, every eight years, a horse saddle. He described his job, for which he was paid $1 a month, as being "to stop lava from flowing down. Let the volcano breathe, but not cough."