The Zaydi imams maintained their rule over Sanaa until the mid-19th-century when the Ottomans relaunched their campaign to control the region. In 1835, Ottoman troops arrived on the Yemeni coast under the guise of Muhammad Ali of Egypt's troops. They did not capture Sanaa until 1872 when their troops led by Ahmed Muhtar Pasha entered the city. The Ottoman Empire instituted the Tanzimat reforms throughout the lands they governed.