Nepal has been plagued by political instability over the past decades, with 32 governments taking office since 1990 and none completing a five-year term. The country was ruled by monarchs from various dynasties until 1951, when a parliamentary democracy was established. King Mahendra suspended the constitution and banned political parties a decade later, and King Birendra held power until 1990, when the absolute monarchy was reduced to a constitutional one. King Barendra and eight other royals were killed in a 2001 palace massacre by his son, Crown Prince Dipendra, who later turned the gun on himself. The centrist Nepali Congress, the country's oldest political party, won the clear majority required to form the government in 1991 and 1999, but did not last its full term either time due to internal and inter-party squabbling. In 2008, a special assembly dominated by former Maoist rebels voted to abolish the 239-year-old monarchy. The shift to a republic failed to create political stability.