Inhambane was the most southerly settlement that can be considered part of the Kilwan trading empire. In its later years, the Sultans of Kilwa began falling into the hands of their ambitious ministers (viziers and emirs), who played the roles of kingmakers, and "de facto" rulers, and occasionally tried to foist themselves (or one of their family members) on the throne, in competition with the royal dynasty. The most successful was probably Emir Muhammad Kiwabi, who ruled Kilwa for nearly two decades through several sultans, including himself at one point. Throughout his long 'reign', Emir Muhammad fought an on-again and off-again battle with his nephew, Hassan ibn Suleiman (son of an earlier vizier). Muhammad had, in fact, tried to install Hassan as sultan a couple of times, but it met tremendous resistance from the population of Kilwa. Eventually, Emir Muhammad decided that, in the interests of constitutional propriety and civic peace, Kilwa sultans should always come from the royal dynasty, not families of viziers. Muhammad held that line more-or-less down to the end, thwarting Hassan's ambitions. The last sultan installed by Emir Muhammad before his death was the royal prince al-Fudail ibn Suleiman in 1495. The man who succeeded to Muhammad's post, Emir Ibrahim (known as "Mir Habrahemo" in Barros, "Abraemo" in Goes), helped al-Fudail crush the ambitious Hassan once and for all in a great battle outside Kilwa. But it was not long after this battle that Emir Ibrahim is said to have betrayed and murdered sultan al-Fudail. Rather than declare himself sultan, Ibrahim took power merely with the title of "emir", and claimed to be exercising rule in the name of a son of an earlier sultan Suleiman (ibn Muhammad?) of the old royal dynasty. That no one had seen or heard of this absent prince for years was quite convenient for Emir Ibrahim. Emir Ibrahim's usurpation was met with shock not only in Kilwa, but in the vassal cities as well. Emir Muhammad had (belatedly) recognized the importance of constitutional propriety for peace in the Kilwa Sultanate. Emir Ibrahim's murderous coup had run roughshod over it. Most of the local governors of the Kilwa vassal cities, many who were either relatives or had owed their positions to Emir Muhammad and the royal dynasty, refused to acknowledge the usurpation of Emir Ibrahim, and began charting an independent course for their own city-states.