Pietro Ziani was forty-second Doge of Venice from 1205 to 1229. He was the son of Sebastian Ziani, and succeeded Enrico Dandolo. Ziani was first doge to demand an oath from the Venetian colony in the Latin Empire in Constantinople, established after the Fourth Crusade. In 1210 he signed a treaty with the despotate of Epirus under Michael Comnenus to allow free trade to Venetian traders.