Dublin’s Viking Beginnings
In 841, the Vikings established a fortified base in Dublin, transforming the settlement into a thriving commercial hub under leaders like Olaf Guthfrithson during the 10th century. Despite repeated attacks from native Irish forces, Viking control persisted until the Norman invasion in 1169. The surrounding region, known as Dyflinnar skíði or "Dublinshire," served as the Norse hinterland.

During this period, Dublin’s economy partially relied on the slave trade, peaking in the 9th and 10th centuries. Vikings and Gaelic raiders captured prisoners from Wales, England, Normandy, and other regions, selling them into slavery. This dark chapter played a significant role in the city's early economic growth.

Norman Conquest and Anglo-Norman Rule
The political landscape shifted when Diarmait Mac Murchada, King of Leinster, enlisted the help of Strongbow (Richard de Clare, Earl of Pembroke) after his exile by Ruaidrí Ua Conchobair, King of Connacht. Following the conquest of Dublin and Mac Murchada's death, Strongbow declared himself King of Leinster.

In response to Strongbow’s success, Henry II of England launched a larger invasion in 1171, asserting English sovereignty. This marked the establishment of the Lordship of Ireland and led to the creation of the County of Dublin, which included surrounding liberties.

Dublin Castle was founded in 1204 under King John of England as the heart of Anglo-Norman administration. By 1229, the city had its first Lord Mayor, and its population grew to 8,000 by the late 13th century, prospering as a trade center despite threats from native Irish clans and external attacks, such as the 1317 siege by Robert the Bruce of Scotland.

Plague and Survival
The Black Death reached Dublin in 1348, devastating the population over the next decade. However, the city rebounded, remaining the center of English-controlled Ireland, known as the Pale.

Renaissance and Tudor Reformation
The Tudor conquest of Ireland in the 16th century brought a renewed focus on Dublin. Queen Elizabeth I sought to Protestantize the city, establishing Trinity College in 1592 and converting Catholic landmarks like St. Patrick's and Christ Church cathedrals into Protestant institutions.

By 1640, Dublin’s population had grown to 21,000, but a plague from 1649–1651 reduced it by almost half. Recovery followed, fueled by the wool and linen trade with England. By 1700, Dublin’s population exceeded 50,000, with 12,000 people employed in wool manufacturing by 1698.

Dublin’s medieval era showcases a city resilient against challenges, evolving through Viking dominance, Norman governance, and Tudor reforms into a flourishing trade and administrative center.