Northern Myanmar is strategically important to Beijing as a supply corridor and as a buffer between China's ethnically diverse southwestern provinces and southern Myanmar. The heightened tension in northern Myanmar in the past several years presented Beijing with challenges regarding border security and maintaining a balance between Naypyidaw and various ethnic forces with strong connections to Beijing. Myanmar armed forces have recently intensified attacks against the ethnic Kachin Independent Army. The spillover of fighting in Kachin region affects stability along China's southwestern border, an area with a large ethnic population. Tens of thousands of Myanmar refugees have already poured into Yunnan province. The spillover also affects China's investments in Kachin and, more important, increasingly challenges Beijing's ability to influence ethnic groups in the region, many of which have cultural and ethnic connections to China and remain under Chinese economic and political influence. The region along the border between Myanmar and China historically served as a buffer region and key supply corridor under strong Chinese influence. Historical ties with various ethnic groups that were never fully consolidated under Myanmar's central government allowed Beijing to manage its relations and influence in northern Myanmar to pursue and protect its broader interests in the country. Since China's relationship with the country's military government normalized in the 1990s, Beijing withdrew its direct support of ethnic rebels in northern Myanmar and assumed the role of mediator to maintain a balance between Myanmar's central government and the ethnic forces.