" Saleh had his own battles to fight, most notably with a rebellious group called Ansar Allah (“Supporters of God”). Its base were the Zaydi tribes in the rugged mountains of northwest Yemen (with some spillover into the very south of Saudi Arabia). The Zaydis represent about 40 percent of the Muslim population of Yemen. They are considered close to Shia, though with doctrines different from those of Iran, and with some affinities to Sunni. "

― Daniel Yergin , The New Map: Energy, Climate, and the Clash of Nations