Nobody knows exactly when the first people came to Ireland. Using radiometric dating, scientists found that a bear bone with knife marks was 12,500 years old. It is likely that people lived in Ireland then. By 7900 BCE, hunter-gatherers (people who ate wild plants and animals) lived in Ireland. This time was called the Stone Age. Around 4000 BCE, they started making farms with animals and plants. They made pottery, stone tools, wood houses, and large tombs. The Bronze Age started around 2500 BCE. People learned to make things out of metals like bronze, gold, and copper, but it was mostly only rich people who had them. People also started weaving and working with leather. Large rooms were built to store metal weapons. The Iron Age started around 600 BCE or earlier, when people started making iron tools. During the Iron Age, Celts came to Ireland, so they started speaking Celtic languages. The Celts brought their style of art with them. Between 1 and 400 CE, Roman soldiers may have invaded Ireland, but Ireland did not join the Roman Empire. About five kings each ruled a large part of Ireland.
In the 300s CE, Christianity and writing were both brought to Ireland. Saint Patrick was famous for spreading Christianity in Ireland in the 400s, but he was not the first Christian in Ireland. For the next 300-400 years, more Irish people became Christian. Christian monks from other countries came to Irish monasteries. Some monasteries grew into towns. The main buildings from 400-800 CE were round forts (raths or ringforts) made of dirt, with houses inside. Most of the forests were cut down to make farms. There were some new kingdoms in this time. The kingdom of Uí Néill in north Ireland took over the area called Tara, then ruled over all the other kingdoms. They were called the high kings.
By 800 almost everyone was Christian. They were called Gaels and they spoke the Gaelic language. In 795, the Vikings, sailors from Scandinavia, invaded and stole from many towns. The Vikings ruled over Irish kings. They built Dublin and other cities and towns on the coast. In 902 the Christian Irish armies pushed out the Vikings, but in 917 the Vikings came back to start a new kingdom of Dublin. Over time, Vikings started new kingdoms. In the 1000s and 1100s, the Vikings either left or became part of Irish culture.
Brian Boru, a King of Munster, fought against Leinster and became the high king in the early 1000s. After that, high kings came from the four provinces: Munster, Leinster, Ulster, and Connacht. Each province also had its own king.
In the 1100s, Ruaidrí Ua Conchobair was the high king. He forced Diarmaid Mac Murchada, the king of Leinster, to leave his kingdom. Diarmaid asked Henry II, a Norman king of England, to help him get his land back. Henry agreed, so an army of Norman (and Welsh) knights invaded Ireland in 1167. Richard de Clare, called Strongbow, led the knights. Henry thought the Norman knights and Strongbow were too powerful, so he decided to take over Ireland. He traveled to Ireland with his own fleet in 1171. Henry conquered Ireland and gave it to his youngest son John. Henry thought John would never be king of England, so he made John Lord of Ireland. But John became king of England in 1199 after all his brothers died. After that, Ireland was ruled by the English king. Norman lords from England started taking over more of Ireland. They mostly lived near the east and south coasts, and some land was still ruled by Irish kings.
The Norman lords built new castles and towns in their land. Many people came from England to Ireland for more land. The English, Norman, or Anglo-Norman lords broke up land into areas called manors. They put fences around farms so everyone would know who owned the farm. Farms were made better so they could grow more in a smaller area. The Anglo-Normans planted more wheat and raised more sheep. The population grew quickly. In 1297, Anglo-Normans started the Irish Parliament, a gathering to make laws.
The Gaelic Irish often tried to take control from the Anglo-Normans. In 1315, Edward Bruce, a lord from Scotland, allied with the Irish to fight the Anglo-Normans. In 1318 the Anglo-Normans won the war. But the Anglo-Norman rulers became weaker. By 1500, England only controlled a small part of eastern Ireland, called the Pale. In the rest of Ireland, people spoke Irish and had Irish culture.
Ireland had a governor (ruler) who was supposed to be loyal to the King of England. In the 1530s, Thomas Fitzgerald, the governor, rebelled against England. Because of this, King Henry VIII of England wanted more power. In 1541, he declared himself King of Ireland instead of Lord of Ireland. The English built military forts in Ireland. English settlers moved to areas in Ireland called plantations. They used English laws and took over a lot of Ireland. During the Nine Years War in the 1590s, Irish soldiers from Ulster fought the English.
Most of the Irish people were Catholic. The settlers were mostly Protestant. In Ulster, the largest plantation, settlers were mostly Presbyterians from Scotland. In the other provinces, the settlers were mostly Anglicans from England. English kings and the English Parliament wanted the Irish people to be Anglican. They made the Church of Ireland, a branch of the Anglican Church. The Penal Laws of the 1600s punished Irish people who did not follow the Church of Ireland. The Anglicans grew more powerful. This time was called the Protestant Ascendancy. That was the end of Gaelic Ireland.
In the 1700s, the Catholic people of Ireland were poor peasants. They mostly ate potatoes, and they were not allowed to own land. There were rebellions against landlords and English rule, but they mostly failed. In 1801, the Acts of Union joined Ireland with Great Britain, forming the United Kingdom of Great Britain and Ireland (UK). The Irish parliament became part of the United Kingdom parliament in London.
In 1831, the government forced primary schools to teach in English, not Irish. Children were punished if they spoke Irish in school. People had to speak English if they wanted a good job. From 1845-1849, a disease killed potato plants, which caused the Great Famine, or the Irish Potato Famine. About a million people starved to death, and a million more moved to other countries. The famine hurt Irish speakers the most, because they were poor. More people switched from speaking Irish to English. Some say people starved because crops in Ireland were sold to other countries. These crops could have fed people in Ireland. Many Irish people were forced to leave their land because they could not pay rent to the landlords. Some had to work in factories set up by the government, because of the Irish Poor Laws. From the 1870s to the 1890s, there was violence between the Land League and the government. The Land League wanted lower rent and they wanted to buy land.
In the late 1800s and early 1900s, the British government made it easier for Irish people to buy land. In 1886 the Liberal Party tried to make a new parliament for Ireland. This idea was called Home Rule. However, Parliament did not allow Ireland to have Home Rule. Around 1900, Irish people were split into Nationalists, who wanted Home Rule or independence, and Unionists, who wanted to be ruled by Britain. Nationalists were mostly Catholics who lived in rural areas. Unionists were mostly Protestants who lived in cities. The Unionists worried they would lose their rights if Ireland had its own government. In some parts of Ireland, Unionists were mostly rich. But in Ulster, many Unionists were workers who wanted the upper class to have less power.