A humanitarian catastrophe is unfolding along the Bangladesh-Burma border. More than 370,000 Rohingya have fled a violent military crackdown in Burma, also known as Myanmar, and are crowded in desperate conditions in Chittagong, Bangladesh. This political and humanitarian emergency is acute, volatile and could breed instability in Bangladesh and beyond.

Here are five points essential to understanding the complex and multidimensional crisis.

1. Civilians are paying the price for a small, armed insurgency

For decades, Burma has systematically persecuted the Rohingya, an ethnic and religious minority living in the state of Rakhine; at times, that persecution has included violence. But the current scale of attacks is unprecedented. So what set it off?

The simplest explanation is that on Aug. 25, the Arakan Rohingya Salvation Army (ARSA), an armed rebel group of several hundred fighters, launched attacks on more than 25 military and border police posts, reportedly killing a dozen Burmese security personnel. Led by an ethnically Rohingya but Pakistan-born and Saudi-raised militant named Ata Ullah, ARSA claims to seek an autonomous Muslim state for the Rohingya. Burma classifies it as a terrorist group. It’s not clear how much support ARSA actually claims among the Rohingya..