The Houthis had formed a tactical alliance with Ali Abdullah Saleh, Yemeni President in 1990-2012, after he was deposed in the 2011 Yemeni revolution to which Houthis themselves had contributed. Houthis were also dissatisfied with the new Yemeni president Abdrabbuh Mansur Hadi who was appointed by the Gulf Cooperation Council and didn't let them a share in the government among other reasons. The dissatisfaction turned into widespread protests when Hadi government ordered removal of fuel subsidies. Houthis organized mass protests and advanced into the capital, Sanaa, taking over government buildings but Hadi and his cabinet finally suddenly resigned leaving office in the hands of Houthis. Soon afterwards, the Saudis led a military intervention in Yemen upon Hadi request against Houthis to restore him to power. Houthis and Saleh forces shared administration of the capital and the country since then.
Pro-Saleh forces controlled Southern Sana'a while Houthis were in control of the northern part of the capital. The tactical alliance between Saleh, who was deposed in 2012, and the Houthis has often appeared fragile, with both groups suspicious of each other's ultimate motives and sharing little ideological ground.