bombed Yemen, destroying (they said) they Yemeni air force. The Yemeni air force had gone over to the side of the Houthis, the mainly Shiite militias that recently overran the capital and declared themselves the government. The land they dominate is shown in green above. The Saudis are supporting a different set of militias, the Hadis, whose lands are shown in pink. Each side is led by a recent President of the country.
I can't seem to find out how this corresponds to religious divisions. The articles I have read about Yemen's history before the 1960s all discuss the division in terms of various tribes and sheikhs and say nothing about Sunnis vs. Shiites. Which is interesting in itself.
But, anyway, things don't look good for Yemen. If the Saudis and Iran step up their support for their allies in the country we could see another major civil war dragging on for years, providing yet more opportunities for al Qaeda and the Islamic State to seize territory or just foment their plans with impunity.