Narbuta Bey’s son Alim was both ruthless and efficient. He hired a mercenary army of Tajik highlanders, and conquered the western half of the Fergana Valley, including Khujand and Tashkent. He was assassinated by his brother Umar in 1811. Umar’s son, Mohammed Ali (Madali Khan), ascended to the throne in 1822 at the age of 12. During his reign, the Khanate of Kokand reached its greatest territorial extent. The Kokand Khanate also housed the Khojas of Kashgar like Jahangir Khoja. In 1841, the British officer Captain Arthur Conolly failed to persuade the various khanates to put aside their differences, in an attempt to counter the growing penetration of the Russian Empire into the area. In November 1841, Captain Conolly left Kokand for Bukhara in an ill-fated attempt to rescue fellow officer Colonel Charles Stoddart, and both were executed on 24 June 1842 by the order of Emir Nasrullah Khan of Bukhara.