History of the Republic of Venice of the Sea" ceremony was established in this period. Orseolo died in 1008. Venice's control over the Adriatic was strengthened by an expedition by Pietro's son Ottone in 1017, by which time Venice had assumed a key role in balancing power between the Byzantine and Holy Roman Empires. During the long Investiture Controversy, an 11th-century dispute between Henry IV, Holy Roman Emperor and Pope Gregory VII over who would control appointments of church officials, Venice remained neutral, and this caused some attrition of support from the Popes. Doge Domenico Selvo intervened in the war between the Normans of Apulia and
Periplus of the Erythraean Sea believed to be the location of the ancient trade center of Opone. Ancient Egyptian, Roman and Persian Gulf pottery has been recovered from the site by an archaeological team from the University of Michigan. Opone is in the thirteenth entry of the "Periplus of the Erythraean Sea", which in part states: In ancient times, Opone operated as a port of call for merchants from Phoenicia, Egypt, Greece, Persia, Yemen, Nabataea, Azania, the Roman Empire and elsewhere, as it possessed a strategic location along the coastal route from Azania to the Red Sea. Merchants from as far afield as Indonesia and