A 1989 split in the Communist Party of Burma (CPB), established in 1939 to spearhead the struggle against Britain and colonialism, led to the creation of the United Wa State Army (UWSA), the armed wing of the United Wa State Party. In the 1970s and 80s, with backing from China, the CPB had constituted the largest military threat to the regime in Rangoon (now Yangon). The Wa provided the bulk of the CPB's ground forces. Thousands were killed in spectacular attacks in which waves of CPB soldiers threw themselves against Burmese positions. According to some observers, more than 25 per cent of Wa soldiers died in the fighting and the prospect of losing more made several Wa leaders rebel. At the same time, Beijing's support began to wane. The CPB split along ethnic lines into four factions, with the UWSA remaining the strongest. The UWSA then signed a ceasefire with the Burmese authorities, who, weakened by the 1988 democracy uprisings, readily accepted the UWSA's terms. In addition to self-rule, the UWSA was allowed to keep its weapons and trade in whatever it wanted. It did not take the UWSA long to remember that the most lucrative business in the Wa hills was the production and sale of illegal drugs, a trade that had long vexed the CPB.