Yemen's humanitarian catastrophe, often described as the world's worst, has its roots in a political transition that unraveled into full-scale war. Following the 2011 Arab Spring protests that forced President Ali Abdullah Saleh from power, a fragile transition government led by Abdrabbuh Mansur Hadi struggled to consolidate authority. The Houthi movement, formally known as Ansar Allah, exploited widespread discontent with economic deterioration and political exclusion to seize the capital Sana'a in September 2014. By March 2015, a Saudi-led coalition intervened militarily to restore the internationally recognized government, transforming what had been an internal political crisis into a devastating proxy war involving regional and international powers.
The conflict has produced one of the largest displacement crises in the Middle East. Over 4.5 million Yemenis have been internally displaced since 2015, with many displaced multiple times as front lines have shifted. Unlike Syria and Ukraine, Yemen's displacement has been overwhelmingly internal, the country's geographic isolation, surrounded by sea and the Saudi border, has limited options for cross-border flight. Displaced populations concentrate in overcrowded urban areas and informal settlements, where they face acute shortages of shelter, water, sanitation, and healthcare. Host communities, themselves impoverished, bear enormous burdens with minimal external support.