This month, a troupe of 100 musicians, dancers, acrobats and robed actors is performing an Ottoman-style spectacle near Topkapi Palace, once home to the sultans. An exhibition of Ottoman poetry is on display at Istanbul's international airport. Ottoman cuisine, a fusion of flavors from old imperial lands, is in vogue.

It's quite a turnaround. For most of the last century, Turks were told to look askance at the Ottoman Empire. Nostalgia for the 1453 conquest of Constantinople and other early triumphs was fine — but the excesses of the sultans were the stuff of decay, no model for modern Turkey.

Turkey is a regional power that no longer sees itself as a junior partner of the West. Its diplomats and entrepreneurs reach out to Iraq, Iran, Syria and other lands once ruled from the Ottoman court. The roots of this confident campaign lie partly in the protocol, pluralism and Islamic piety of the imperial past....