Christian Ethiopia’s political and territorial decline, which began in the sixteenth century, continues throughout this period due in part to encroachment by pastoral peoples and emergent Muslim states such as Harar, in western Ethiopia. Efforts to unify the Ethiopian Church and restore security and prosperity to the kingdom produce a period of artistic florescence centered at the capital city of Gondar. Along the East African coast, first Portugal and then the sultanate of Oman gain control of Swahili economic centers; Mombasa, in modern-day Kenya, becomes an important state in the eighteenth century under Omani rule. The East African interior, in present-day Rwanda, Burundi, Uganda, and western Kenya and Tanzania, witnesses the development of large states made powerful by trade and improved agriculture. At this time, emblems of leadership imported from the coast and Central Africa are adopted for use throughout the region.