Mohammad's reign was marked by a continued weakness of the crown and tribal infighting as part of the second civil war of the Safavid era. An important figure in the early years of Mohammad's reign was his wife Khayr Al-Nisa Begum, who helped secure her husband's reign. However her efforts to consolidate central power brought about opposition from the powerful Qizilbash tribes, who had her murdered in 1579. Mohammad has been described as "a man of refined tastes but weak character". As a result, Mohammad's reign was characterised by factionalism, with major tribes aligning themselves with Mohammad's sons and future heirs. This internal chaos allowed foreign powers, especially the rivalling and neighboring Ottoman Empire, to make territorial gains, including the conquest of the old capital of Tabriz in 1585. Mohammad was finally overthrown in a coup in favour of his son Shah Abbas I.