Symbolism. The key national symbols are Buddhist, despite the fact that only around 60 percent of the population is Buddhist. Before the revolution in 1975, Buddhism and the monarchy were linked as key symbols. The Communist regime tried to substitute purely secular national symbols, and a calendar of mostly secular holidays was instituted. The flag of the first independence movement in 1945, the Lao Issara, replaced that of the Royal Lao Government (RLG). With the collapse of communism, the state has reverted to purely nationalist symbols; this "retraditionalizing" of the regime has meant a greater prominence for Buddhism. The national day of December 2 was celebrated after the revolution, but has been eclipsed by the celebration of the That Luang Festival. The That Luang stupa in Vientiane, built by the revered King Sethathirat, is one of the most sacred spaces and is recognized by all groups. Other national icons are also Buddhist, but some, such as the megalithic jars from the Plain of Jars, point to complex origins. Much of this iconography was pioneered by the RLG, including that associated with "hill tribes," who are typically presented in their "national dress." In general, national culture symbols are drawn fro Lao culture, suggesting that other ethnic groups are required to assimilate these symbols. This is a source of low-key contention in the country. The appropriation of "old regime" symbols has muted some of the conflict between refugee Lao and the LPDR (Lao People's Democratic Republic), but has led to debates over how much of the past to "revive."