With feudalism Pula lost its centuries-old Municipal tradition but during the 10th and 11th century Pula got back its free Municipality institutions. Later on, during the Middle Ages, Pula was under the influence of the two dominant powers in the north Adriatic sea: the Aquileia Patriarchs and the Venetian Republic. In 1028 Pula became independent from the Church of Ravenna and dependent on the Aquileia Patriarchs.

Pula signed its first friendship agreements with Venice in the 11th century and from the 12th till the 14th century was several times involved in the battles between the Mediterranean maritime States: Pisa and Genoa forces.

In 1145 Pula tried to exit from the agreement with Venice but Doge Pietro Polani won that battle and forced Pula to remain dependent on Venice. The agreement with Venice limited Pula’s commercial activity.

In 1150 Venice occupied Pula again and forced it to renew its last fidelity agreement. In 1155 Pula refused to pay Venice taxes as per their previous agreements and so the town was occupied again and the walls were demolished.

In 1193 Pula was occupied by Pisa forces. In reality, it is likely that Pula allowed Pisa’s ships and soldiers to enter the town because Pula was again in disagreement with Venice. Venice reacted and defeated Pisa’s and Pula’s forces. The town walls of Pula were demolished again. During that whole period Pula remained a free Municipality.

During the 12th century the Arab geographer, Edrisi, visited Pula. In his notes Pula was named Bulah and was described as beautiful, big, full of people and with very nice ships in the harbour.

Pula conserved its Municipality status for several centuries but in 1198 was forced to accept the Venetian Rector Ruggero Morosini. Bishops gave Morosini land and several villages that were grouped into the Morosini feud.

In 1209 the Aquileia Patriarchs received the title of Marquis of Istria and the Bishops of Pula became representatives of the Aquileia Patriarchs. At the time the Bishops of Pula assumed the title of Counts of Galizana. Few years later the Aquileia Patriarchs Volchero tried to impose their authority in Pula but were unsuccessful. In 1233 Pula was forced to accept the restrictions imposed by the Aquileia Patriarchs.

In 1242 Pula refused to produce and give ships to Venice as agreed in 1145 and a year later Venice occupied Pula yet another time and once more imposed a fidelity agreement on Pula.

During the 13th century there were two families with significant followers in the town: the Jonatasi family, that were on the Venetian side and the Sergi family, later on named Castropola, that were on the side of the Aquileia Patriarchs.

The Aquileia Patriarchs built a fortress on the hilltop of the old town for the Sergi family and gave the Sergi family important territories around Pula. The newly built fortress became the residence of the Sergi family.

After that the Sergi family changed their name into Castro Polae that later on became Castropola. At the time the Castropola family controlled: all the area around Pula, Vodnjan, Mutvoran, Bale, Svetvincenat and Dvigrad.

The origins of the Castropola family are not clear. One assumption is that they are the successors of an important Roman family that lived in Pula since Pula’s foundation and the other one is that their origin is Frank and that they established themselves in Pula at the beginning of the 9th century. Their family tree dates back into the 12th century and starts with Bonifacio Sergi.

In 1318 Venice established the Istrian Riviera Captaincy and nominated Nicolo’ Badoer as the Captain. People from Pula captured and killed Captain Badoer at sea nearby Bale. The Castropolas knew that Venice would react to these facts and asked the Aquileia Patriarchs to help and protect them through their diplomacy channels in Venice. In the end Pula and the Castropola family had to swear loyalty to Venice.

In 1331, during a religious ceremony on Saint Friday, Andrea Jonatasi and a group of people that were loyal to him organized a rebellion against the Castropolas.

In reality they were masked with religious ceremonial dresses and killed all Castropolas that were present at the ceremony. They occupied the Castle and according to the story only a kid survived this attack.

That year the Castropola family lost power and the town became a part of Venice. Pula at the time had 6000 inhabitants. After 1331 Pula nominated a Rector or Count as the head of the Municipality and this practice remained in place until the fall of Venice in 1797. The first Count of Pula was Bertuccio Michiel.