An alliance of Myanmar ethnic minority groups is waging a lightning offensive against the military which analysts say is the biggest battlefield challenge to the junta since it seized power. The fighting across northern Shan state has displaced more than 23,000 people according to the UN, and seen dozens of military outposts fall. The rugged jungle region has long been a bitterly contested theatre of conflict between ethnic armed groups and military-aligned militia fighting over lucrative criminal enterprises ranging from drug smuggling and casinos to prostitution and cyber scams. A patchwork of kingdoms ruled by local sawbwas (“lords of the sky”), the Shan states came under the control of Burmese kings around the 15th and 16th centuries. During colonial rule, the British gave the region a large degree of autonomy and built their summer capital, May Myo, in its cool hills. Today the town — renamed Pyin Oo Lwin after independence — is home to the military’s premier officer training school, the Defence Services Academy, which trained many of the current junta leadership. Soon after independence Chinese nationalist troops retreating from Mao Zedong’s communists made several incursions into Burma through Shan state, leading to bloody and repeated clashes with the military. Today a giddying array of ethnic armed organisations that can call on tens of thousands of well-armed fighters control swathes of Shan state. Some administer autonomous enclaves granted to them by previous juntas, which analysts say are home to casinos, brothels and weapons factories. The Ta’ang National Liberation Army (TNLA) and the Myanmar National Democratic Alliance Army (MNDAA) have provided training and support to “People’s Defence Forces” that have sprung up to battle the military. Current junta chief Min Aung Hlaing made a name for himself as a regional commander in 2009, prising the MNDAA from the town of Laukkai, just inside the border with China.