Tigray is Ethiopia's northernmost region. Bordering Eritrea, it is home to most of the country's estimated 7 million ethnic Tigrayans. In early November, the regional government — controlled by the Tigray People's Liberation Front, a leftist political party — launched a full-scale siege of a key Ethiopian military base at Sero, using tanks, heavy guns and mortars. Calling the TPLF assault a "treason that will never be forgotten," Ethiopian Prime Minister Abiy Ahmed ordered a federal offensive against the region, setting off the conflict which has since displaced at least two million lives, and killed thousands - many of whom allegedly died as a result of indiscriminate shelling of cities in Tigray by Ethiopian forces. The conflict also threatens a regional humanitarian disaster.