This is what we found on Wikipedia regarding the Hop-On Hop-Off Al Madinah 24 Hours:

The Houthis, officially known as Ansar Allah, is a Zaydi revivalist and Shia Islamist political and military organization that emerged from Yemen in the 1990s. It is predominantly made up of Zaydis, whose namesake leadership is drawn largely from the al-Houthi family. The group has been a central player in Yemen's civil war, drawing widespread international condemnation for its human rights abuses, including targeting civilians and using child soldiers. The movement is designated as a terrorist organization by some countries. The Houthis are backed by Iran, and they are widely considered part of the Iranian-led "Axis of Resistance".

Under the leadership of Zaydi religious leader Hussein al-Houthi, the Houthis emerged as an opposition movement to Yemen president Ali Abdullah Saleh, whom they accused of corruption and being backed by Saudi Arabia and the United States. In 2003, influenced by the Lebanese Shia political and military organization Hezbollah, the Houthis adopted their official slogan against the United States, Israel, and the Jews. Al-Houthi resisted Saleh's order for his arrest, and was afterwards killed by the Yemeni military in Saada in 2004, sparking the Houthi insurgency. Since then, the movement has been mostly led by his brother Abdul-Malik al-Houthi.

The organization took part in the Yemeni Revolution of 2011 by participating in street protests and coordinating with other Yemeni opposition groups. They joined Yemen's National Dialogue Conference but later rejected the 2011 reconciliation deal. In late 2014, the Houthis repaired their relationship with Saleh, and with his help they took control of the capital city. The takeover prompted a Saudi-led military intervention to restore the internationally recognized government, leading to an ongoing civil war which included missile and drone attacks against Saudi Arabia and its ally the United Arab Emirates. Following the outbreak of the Gaza war, the Houthis began to fire missiles at Israel and to attack ships off Yemen's coast in the Red Sea, which they say is in solidarity with the Palestinians and aiming to facilitate entry of humanitarian aid into the Gaza Strip.

The Houthi movement attracts followers in Yemen by portraying themselves as fighting for economic development and the end of the political marginalization of Zaydi Shias, as well as by promoting regional political–religious issues in its media. The Houthis have a complex relationship with Yemen's Sunnis; the movement has discriminated against Sunnis but has also allied with and recruited them. The Houthis aim to govern all of Yemen and support external movements against the United States, Israel, and Saudi Arabia. Because of the Houthis' ideological background, the conflict in Yemen is widely seen as a front of the Iran–Saudi Arabia proxy war.